Fix another upload-pack deadlock

See merge request !118

Thanks Nick for pointing out that exec.Cmd can take care of all the
copying for us.

This reverts commit bba7d53e, reversing
changes made to 815be1cc.

Add webpack dev-server support

Closes #104

See merge request !121

Terminate terminal session after configurable upper time limit

Closes #86

See merge request !107

Remove useless variable

See merge request !117

We forgot to remove this variable during a refactor.

Release v1.3.0

See merge request !116

Fix stalled HTTP fetches with large payloads

Closes #92, gitlab-ce#25916, and gitlab-com/infrastructure#941

See merge request !110

Add helper.IsContentType and use it everywhere

Closes #90

See merge request !114

Add unit test for upload-pack handling

See merge request !111

Allow nested namespaces in git URLs

Closes #74

See merge request !80

For fetches over HTTP, Workhorse executes git-upload-pack and first
attempts to send all the input data to stdin before reading from the
stdout pipe. However, when the payload is large, the stdout pipe may
fill up, causing git-upload-pack to stop reading from stdin. Workhorse
will then be deadlocked, since it will be waiting to send more data
to a buffer that will never be drained.

An addition side effect is that git-upload-pack processes also get left
around. These processes are cleaned up only after Workhorse is
restarted.

This fix modifies the git-upload-pack behavior to consume the entire
HTTP input first so that reading the data from stdout and sending the
reply can be performed in a separate Goroutine.

Closes #92

Closes gitlab-org/gitlab-ce#25916

Closes gitlab-com/infrastructure#941

Proxy GET /info/refs to Gitaly

See merge request !105