Add task lists to issues and merge requests

Raise on forgery

Fixes #1572

See merge request !1156

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

Improve autolink

Fixes #1649

See merge request !1155

Prevent PG::Error exception

Prevent PG::Error exception when check commit reference on commit

Fix #1646

See merge request !1154

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

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

Gitlab git bump

Fixes #1643

See merge request !1153

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

[minor-refactor] Remove unused title parameter on merge request creation helper.

Add tests for the new task list functionality in the Markdown parser and
in issues and merge requests.

Make the Markdown parser recognize "[x]" or "[ ]" at the beginning of a
list item and turn it into a checkbox input.  Users who can modify the
issue or MR can toggle the checkboxes directly or edit the Markdown to
manage the tasks.  Task status is also displayed in the MR and issue
lists.

Make Spinach test names consistent [failure unrelated]

Implement cross-project Markdown references

- do not add Feature to feature titles
- titleize feature titles
- put steps on the same path as .feature files
- make feature titles match their path

Fix fa-download icon

Test for the correct link text in cross-project references.

Display the '@' character for links to commits in other projects.

Display the project path in links to issues in other projects that use
an external issue tracker.

Minor ui improvements

See merge request !1152

Add a note to merge requests and issues when they're mentioned by a
merge request, issue, or commit in another project.

Store both the project and identifier of extracted references.  This
prevents `ReferenceExtractor` from returning objects in the wrong
project for cross-project references.

The cross-project reference feature broke the ReferenceExtractor class;
this fixes it.

Enable linking to commits, merge requests, and issues in other projects
by prepending a namespaced project path to the reference.

Add Pushover service integration

That introduce select field type for services options.

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

Conflicts:
	app/views/projects/edit_tree/show.html.haml

New milestone and label links

Fixes #1364

Fixes #1586

See merge request !1145

Signin after confirmation

Fixes #1471

See merge request !1146

Remove outdated comment on the project test seed

Remove assignment without effect.