Signed-off-by: Rémy Coutable <remy@rymai.me>

See https://gitlab.com/gitlab-org/gitlab-ce/issues/3515

Password can now be specified at the same time as the new URL, and the service
template admin pages now work.

This reverts commit b4639754.

It now allows to specify a password at the same time as the new URL, and works
on the service template admin pages.

Supports four different event types all bundled under the "note" event type:

- comments on a commit
- comments on an issue
- comments on a merge request
- comments on a code snippet

1) Adds a DB migration for all services to toggle on push, issue, and merge events.

2) Upon an issue or merge request event, fire service hooks.

3) Slack service supports custom messages for each of these events. Other services
not supported at the moment.

4) Label merge request hooks with their corresponding actions.

Strips the refs/heads/ if any to get just the branchName out of a :ref
e.g.: `refs/heads/feature/newProfile` -> `feature/newProfile`

The TeamCity buildQueue POST data require the branchName attribute
to contain just the branch name (just xyzbranch and not the full
ref in the refs/heads/xyzbranch). With the refs/heads/xyzbranch the
build is triggered and looks like it is working however it always
ompiles the default branch (or master).