Commits without .gitlab-ci.yml are marked as skipped

- Commits without .gitlab-ci.yml are marked as skipped
- Save detailed error when YAML syntax

This also fixes: #3521 #3546 

/cc @jacobvosmaer 


See merge request !1827

Award Emoji

This it first iteration of award emoji feature.
We have plan to extend emoji picker by the next release.

For now, you can add award by clicking to the emoji picker or posting a regular comment with emoji like "👍" and any other. You can post not only emoji that listed in the emoji picker.

See merge request !1825

Add missing dot in confirm modal



See merge request !1645

Improve performance of finding issues with/without labels

The changes in this MR ultimately lead to finding issues with(out) labels being about 2x faster due to:

1. Newly added indexes on `issues.state` and `projects.visibility_level`
2. Adjusting the query so that finding issues for multiple projects is more efficient

See merge request !1787

Improve personal snippet access workflow.

Replaces !1709

Fixes #3258

See merge request !1817

Add option to create merge request when editing/creating a file

Replaces !1611 

Fixes #3059

See merge request !1820

Fix 'Attach a file' link in new tag form

Also removed a little bit of code repetition :)

See merge request !1834

Update gitlab-shell documentation to 2.6.7



See merge request !1836

Do not limit workhorse POST/PUT size in NGINX

Limiting, if any, should happen in gitlab-workhorse.

See merge request !1831

Add link to git-lfs client  [ci skip]



See merge request !1832

Fix bottom position of scroll buttons in build log page

Look at the up/down buttons as well as the **Enable Autoscroll**.

The **Enable Autoscroll** could also be alligned with the right grey box.


## Before

![autoscroll_before](/uploads/f410dc353ca66c338d8a29c7c294758a/autoscroll_before.png)

## After

![autoscroll_after](/uploads/015fdf53618a0d6f468d666de1bbab6a/autoscroll_after.png)


\cc @dzaporozhets @creamzy 

See merge request !1792

Limiting, if any, should happen in gitlab-workhorse.

Deploy page should be shown for all pages not just root

Related to change already merged to Omnibus - gitlab-org/omnibus-gitlab!540

This change makes it so the deploy page is shown on all GitLab pages if the page exists. Users will no longer receive the 502 when deploys are happening.

See merge request !1828

- Save detailed error when YAML syntax

When using IssuableFinder/IssuesFinder to find issues for multiple
projects it's more efficient to use a JOIN + a "WHERE project_id IN"
condition opposed to running a sub-query.

This change means that when finding issues without labels we're now
using the following SQL:

    SELECT issues.*
    FROM issues
    JOIN projects ON projects.id = issues.project_id

    LEFT JOIN label_links ON label_links.target_type = 'Issue'
                          AND label_links.target_id  = issues.id

    WHERE (
        projects.id IN (...)
        OR projects.visibility_level IN (20, 10)
    )
    AND issues.state IN ('opened','reopened')
    AND label_links.id IS NULL
    ORDER BY issues.id DESC;

instead of:

    SELECT issues.*
    FROM issues
    LEFT JOIN label_links ON label_links.target_type = 'Issue'
                          AND label_links.target_id  = issues.id

    WHERE issues.project_id IN (
        SELECT id
        FROM projects
        WHERE id IN (...)
        OR visibility_level IN (20,10)
    )
    AND issues.state IN ('opened','reopened')
    AND label_links.id IS NULL
    ORDER BY issues.id DESC;

The big benefit here is that in the last case PostgreSQL can't properly
use all available indexes. In particular it ends up performing a
sequence scan on the "label_links" table (processing around 290 000
rows). The new query is roughly 2x as fast as the old query.

Since this method's returned data doesn't change between calls on the
same IssuableFinder instance we can just memoize this similar to the
"project" method.

This field is queried when filtering issues and due to the lack of an
index would end up triggering a sequence scan.

Improve performance of user profiles, finding groups, and finding projects

This MR improves the following:

* Rendering of profile pages and Atom feeds
* Finding groups (using GroupsFinder & friends)
* Finding projects (using ProjectsFinder & friends)

Initially this MR was intended to only improve rendering of Atom feeds, but over time other fixes were introduced as well as the same code was the cause of all these problems.

See merge request !1790

Check which folders and archives should be packed before passing to tar command.

If user uses backup task with SKIP and skips one of the archives listed(uploads, builds, artifacts) backup create will give an error: `Cannot stat: No such file or directory`.

This MR fixes that by checking for skipped items.
Additionally, compact everything to avoid `TypeError: no implicit conversion of nil into String` errors.

See merge request !1824

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>