Closes #13254

Add notice about variables in build log

Related to: https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/1942

[ci skip]

See merge request !2761

Prevent rasterization artifacts in the logo, and simplify markup.

 - Remove sketch-namespaced attributes.
 - Remove unused groups, and cancel out unnecessary transforms.
 - Use overlap to avoid rasterization artifacts in the logo.
 - Remove viewBox parameter and define paths in their final form.

See merge request !2741

[ci skip]

Freeze constants in Gitlab::Git

See merge request !1730

Smarter flushing of branch statistics caches

This basically ensures we only flush caches of branches whenever we really have to. See commit c514f8b850219cd3e5526e73e1d00e6729e2b466 for the details.

cc @joshfng @rspeicher 

See merge request !2769

Change default smpt port to 465 (default smtps port)

Instead of flushing the behind/ahead counts for all branches upon every
push we now only flush the cache of branches that actually need to have
these statistics recalculated. There are now basically 2 scenarios and
their effects:

1. A user pushes a commit to the default branch, this results in the
   cache being flushed for all branches.
2. A user pushes to a non default branch, this results in _only_ the
   cache for that branch being flushed.

The existing code (Repository#expire_cache) remains backwards compatible
with the previous behaviour, the new behaviour is only applied when a
branch name is passed as an argument. This ensures that when for example
a project is deleted the cache for all branches is flushed.