Refactor upstream

Rationale: the code has become a tangled mess of global variables and
types that hang together when they need not. For example: every HTTP
handler uses a 'gitRequest'?? I want to clean this up and see if I can
move some things into internal packages.

Apart from using internal packages we now use http.Handler where we can,
and fewer global variables.

See merge request !20

We need to use `$(shell find` to find files from all subdirectories

Conflicts:
	main.go

remove make warning

When building gitlab-workhose a warning is printed out. This merge request fixes the warning

```
go build -ldflags "-X main.Version 0.5.1-20160103.233349" -o gitlab-workhorse
# _/home/git/gitlab-workhorse
link: warning: option -X main.Version 0.5.1-20160103.233349 may not work in future releases; use -X main.Version=0.5.1-20160103.233349
```

See merge request !22

Fix /api/v3/projects routing error

Non-special API requests were getting special treatment, which
resulted in 500 errors. This change avoids the special treatment and
adds tests that assert that regular API requests should be left alone
by gitlab-workhorse.

See merge request !26

We should test with what actually happens, e.g. foo%2Fbar, not
foo/bar.

Non-special API requests were getting special treatment, which
resulted in 500 errors. This change avoids the special treatment and
adds tests that assert that regular API requests should be left alone
by gitlab-workhorse.

This reverts commit d79f8563.

Kamil pointed out that shallow-copying http.DefaultTransport
accidentally gives us a references to a lot of things that probably
not be shared.

Prevent archive zombies

Interrupted archive downloads were creating zombies, see
https://gitlab.com/gitlab-org/gitlab-workhorse/issues/9

See merge request !25

Episode V: The Archive Zombies Strike Back

The -relativeURL option existed for a while but was never included in
an official release.

Do not show error pages in development mode



See merge request !24