Improve relative URL support

This also removes the -relativeURLRoot setting introduced in 0.5.0.

See merge request !19

The missing trailing / on example.com/gitlab was making us throw a
404.

Make GitLab Workhorse passthrough to Unicorn

It works :)


See merge request !12

Use Go 1.5.2 for tests



See merge request !15

Make error style more uniform

Deprecate 'logContext' in favor of just passing Go error values.

Also adds to missing 'return' statements after a 'fail500' in archive.go.

See merge request !16

No need to check for zero size, this will be handled while storing the object.

Related to gitlab-org/gitlab-ce#3658

See merge request !14

gitCommand: Pass $HOME to git as well

Git has 3 places for configs:

   - system
   - global (per user), and
   - local  (per repository)

System config location is hardcoded at git compile time (to usually
$prefix/etc/gitconfig). Local configuration is usually picked because we
pass --git-dir to subcommand. But global configuration is currently not
picked at all, because HOME env variable is not passed to git.

Pass $HOME through and let git see it's "global" config.

Currently GitLab omnibus stores gitlab user name/email  + "autocrlf =
true" in global config, so missing it should not be a blocker for
receive/send-pack operations. But having it is more correct and can be
handy in the future if/when more git operations are done from-under
gitlab-workhorse.

Having $HOME properly set is also needed when one cannot change system
git config and have to put site-wide configuration into global git
config under $HOME.

That was the case I've hit and the reason for this patch.

See merge request !10