Refactor middleware

- Use gitRequest to store all processed request data
- Drop some headers when creating upstream request

@jacobvosmaer @marin: I still need to write test for it.


See merge request !7

- Use gitRequest to store all processed request data
- Drop some headers when creating upstream request

Serve GitLab uploads via gitlab-workhorse / X-Sendfile

Building on Kamil's work in https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/5

The xSendFile middleware should be reusable for other types of requests too (artifacts, LFS etc.).

See merge request !4

This is based on Kamil's work in
https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/5 .

Replace "auth request" with middleware

This gives us the flexibility we need to also handle regular downloads
and uploads in gitlab-workhorse.

See merge request !6

This gives us the flexibility we need to also handle regular
downloads and uploads in gitlab-workhorse.

Accomodate broken HTTP clients

HTTP header lookups are supposed to be case-insensitive but some
clients do a case insensitive lookup, which breaks because of Go's
header canonicalization.

See merge request !2

Pass LD_LIBRARY_PATH to the git command

As gitlab-shell does in https://gitlab.com/gitlab-org/gitlab-shell/blob/master/lib/gitlab_shell.rb#L126

LD_LIBRARY_PATH is needed when using Software Collections for instance but there are probably many other scenarios that need it as well. It was passed to git (and from git to hooks) by gitlab-shell, and still is for SSH access, but it was not the case anymore for HTTP access with the introduction of gitlab-git-http-server/git-workhorse.


See merge request !1