Fix bug where projects would appear to be stuck in the forked import state

A race condition existed between when Rails committed the `import_status` to
`started` and when the Sidekiq worker forked a project. If this fork were quick,
it's possible that the worker would attempt to move into the `finished` state
before the `started` state took effect.

As mentioned in https://github.com/mperham/sidekiq/wiki/Problems-and-Troubleshooting#cannot-find-modelname-with-id12345,
we can either delay the worker to ensure the DB has a chance to update, or use the nice `after_commit_queue` gem to schedule the task after the state machine commit. See:

* https://github.com/pluginaweek/state_machine/issues/191 
* https://github.com/shellycloud/after_commit_queue


Closes #2736

See merge request !1434

Make sure Unicorn listens on localhost:8080

Some installations from source run into this when upgrading to 8.0.

See merge request !1435

Closes #2692

Fix Error 500 occuring with repositories that have a bad HEAD

A repository could have objects but no valid HEAD, causing `project.commit` to be `nil`.

See merge request !1433

A race condition existed between when Rails committed the `import_status` to
`started` and when the Sidekiq worker forked a project. If this fork was quick,
it's possible that the worker would attempt to move into the `finished` state
before the `started` state took effect.

As mentioned in https://github.com/mperham/sidekiq/wiki/Problems-and-Troubleshooting#cannot-find-modelname-with-id12345,
we should delay the worker to ensure the DB has a chance to update.

Closes #2736

A repository could have objects but no valid HEAD, causing
`project.commit` to be `nil`.

Hook api updates



See merge request !1429

Get CI token from ci projects

This fixes problem when GitLabCiService had different token than stored
in Ci::Project.

See merge request !1425

Update 7.14-to-8.0.md

Update mailroom to 0.5.2

Fixes #2698 and #2711.

See merge request !1424

Add the newrelic-grape gem

This allows us to see a breakdown of API requests in New Relic.

See merge request !1419

Fix default avatar not showing up in network graph

The change in 71cdb249 removed the `/assets` path in the default avatar to eliminate runtime errors, but this was one place where `image_path` was missed. If the user full URL is specified, `image_path` does nothing.

Closes https://github.com/gitlabhq/gitlabhq/issues/9657

See merge request !1411

Add Troubleshooting section to 8.0 docs

[ci skip]

See merge request !1416

Refer to Apache templates in 8.0 update guide

[ci skip]

See merge request !1426

Closes https://github.com/gitlabhq/gitlabhq/issues/9657

Remove CI dashboard

With CI status integrated at GitLab projects page there is no reason to keep it
anymore.
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Part of #2594 

See merge request !1422