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

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.

Download and install go before running tests

This change allows the build to run on 'shared runners'.

See merge request !13

Forward store response to client.

Part of gitlab-org/gitlab-ce#2955

Forward received response to the client.

See merge request !11

Implement multipart form rewriting to support upload offloading

1. This parses multipart form data and saves all found files as files in TempPath. TempPath is received from Rails by calling authorize request. The rewritten multipart form data contains `file.path` where the temporary file is stored, and `file.name` the original name of file as stored in Content-Disposition. The temporary file is removed afterwards, if it's not consumed by GitLab Rails. If the body is not multipart, forward request.

2. All artifacts downloads are offloaded by exposing X-Sendfile-Type extension.


See merge request !5