Explain warnings when using omnibus packages with backup restore

Instead of adding this to the omnibus documentation as proposed [here](https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/392), moving to one central place as part of efforts to have central location for the docs.

See merge request !903

Link to SAML docs from doc index

Without this link, the SAML docs are hard to discover.

See merge request !1882

Without this link, the SAML docs are hard to discover.

Attempt to fix the "I should see that I am [un]subscribed" steps

Makes use of Capybara methods that wait. Hopefully this will fix the
random timing-related failures of this step.

See merge request !853

Add Fuubar as the default RSpec formatter

- Shows how many specs have been run, how many remaining
- Estimates how long is left
- Instantly shows failures
- Looks awesome ✨

![Screen_Shot_2015-06-26_at_1.00.47_AM](https://gitlab.com/gitlab-org/gitlab-ce/uploads/da7c989e04237141d9adb4c4b5898359/Screen_Shot_2015-06-26_at_1.00.47_AM.png)

See merge request !893

Add "Requires Input" JS behavior

This aims to replace all of those `disableButtonIfEmptyField` calls littered throughout views and JS with a simple, clean, markup-based behavior.

While going through all of the old usages, I found a few places where the old behavior wasn't actually working, so... bonus, they work now!

See merge request !900

Remove jasmine:ci task, execute teaspoon directly on CI

See merge request !901

Add a troubleshooting section for backup restore docs, explain about warnings when using omnibus packages.

The "Begin with the selected commit" checkbox requires the submit button
to be enabled, even if the extended SHA1 input field is blank.

These have been replaced by the "requiresInput" behavior.

Rename abilities to correspond contoller/model action names

write_ was renamed to create_
modify_  was renamed to update_

So now in update action we have next code

```
def create
  can?(current_user, :create_issue, @issue)
end

def update
  can?(current_user, :update_issue, @issue)
end
```

See merge request !896

Reorder MergeRequestTabs constructor

The tab was being activated before we set the `[commits|diffs]Loaded`
variable, so even when the `/diffs` route is accessed directly, like
from the "Side-by-side" link, the tab was being loaded from its default
source.

Fixes #1887

See merge request !892

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>

Update permissions for issue tracker management

Don't allow guest or reporter to set assignee, milestone and label when create or update new issue and merge request.
After this change `Guest` and `Reporter` rule is used to report issues but only `Developer` and higher roles can manage issues (schedule milestone, assign to user or close any issue)

Also I removed some duplication code between issues and merge requests and put all issuable partials in one directory

See merge request !890

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

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

write_ was renamed to create_
modify_  was renamed to update_

So now in update action we have next code

def create
  can?(current_user, :create_issue, @issue)
end

def update
  can?(current_user, :update_issue, @issue)
end
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>

added info about GitHub importing

Added info that importing doc also works for GitHub EE.

https://dev.gitlab.org/gitlab/gitlabhq/issues/2410#note_49396

See merge request !1878

Add SAML to list of social_provider

Resolves issue 1888.  Still an issue because the SAML link under Connected Accounts will not have a logo.

See merge request !891

Makes use of Capybara methods that wait. Hopefully this will fix the
random timing-related failures of this step.

The tab was being activated before we set the `[commits|diffs]Loaded`
variable, so even when the `/diffs` route is accessed directly, like
from the "Side-by-side" link, the tab was being loaded from its default
source.

Fixes #1887

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>