Collection of fixes and improvements to GitLab UI

* new design colors
* new font size
* change padding and size of form inputs
* new activity page
* new groups page
* new explore projects page
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

cc @skyruler

See merge request !1239

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

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

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

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

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

Add API method for get user by ID of an SSH key

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

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

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

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

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

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

Implement new design for projects page
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

For #2413

See merge request !1236

Update mail_room to 0.4.2 for better error handling

See merge request !1234

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

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

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

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

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

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

Split starred projects list and activity

In same way like we did with your projects. For consistency
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !1238

Avoid instance variable re-use trouble

This is the quickest/dumbest/safest way I could think of to prevent
the instance variable reuse problems we have on dev.gitlab.org now.

See merge request !1237

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

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

This is the quickest/dumbest/safest way I could think of to prevent
the instance variable reuse problems we have on dev.gitlab.org now.

Remove the filename argument from Content-Disposition header

This MR removes the filename argument from the `Content-Disposition` header to avoid RFC 5987 and RFC 6266 encoding issues. Some browsers (e.g. Internet Explorer) do not properly decode a Unicode string properly, and this can lead to odd filenames in the raw file download. This change allows the browser to determine the filename based on the URL.

For example, if I have a file called `한글한글.pptx` and click to download it with the "Raw" button in the Files section, IE11 will ask:

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/fdb688282c0d4564872deadb44c58b2c/image.png)

If you look at the `Content-Disposition` field, you see this:

![image](https://gitlab.com/stanhu/gitlab-ce/uploads/2b342b83ae1ec61fd31937163ace8ec5/image.png)

Chrome, Firefox, and Safari seem to be able to handle UTF-8 encoded filenames, even though this is not standard.

See: http://greenbytes.de/tech/tc2231/

Closes https://github.com/gitlabhq/gitlabhq/issues/9595

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/1829

I've also submitted a pull request to Rails to support RFC 6266: https://github.com/rails/rails/pull/21461

See merge request !1235

Drone CI service

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/1184#note_1980652

/cc @DouweM

See merge request !1215

RFC 5987 and RFC 6266 encoding issues. This change allows the browser
to determine the filename based on the URL.

See: http://greenbytes.de/tech/tc2231/

Closes https://github.com/gitlabhq/gitlabhq/issues/9595

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/1829

Check if database connection exists when loading application settings

!1217 broke omnibus-gitlab nightly builds. In omnibus-gitlab we precompile assets without a running database.

See merge request !1230

Decouple Gitlab::Markdown from the GitlabMarkdownHelper

This module is now the sole source of knowledge for *how* we render
Markdown (and GFM).

See merge request !1223

Import all Bitbucket issues and sort issues by creation date

Previously only the first 15 Bitbucket issues would be imported. Other issues in the API return call also calls import errors.

Tested by importing 400+ issues from this repo: https://bitbucket.org/ned/coveragepy

API reference here: https://bitbucket.org/site/master/issues/3571/api-issues-sorting-bb-3518

Closes https://github.com/gitlabhq/gitlabhq/issues/9519

See merge request !1226

Also fix a number of issues where author/reporter names were not available.