GitLab

This speeds up re-runs without sacrificing the need to re-run when you
change what repositories you're importing

When you want to have the default project (in order to get snippets, for
instance), but don't want to apply all tickets to it because you're
doing a gradual import, you the configuration needs to respect that.

Set when the space of the phabricator project is one of the confidential
spaces.

Included is the ability to limit users added to just those that took
some action in the included repositories.

Includes:

* Add users to projects in gitlab (needed by new gitlab update)
* Fix ticket links
* Fix snippets that have attachments

This also required getting the mimetype of files and setting them
correctly.

Needs to upload as binary so that gitlab doesn't yell