add websocket support to /container/<name>/attach/ws

This function add the possibility to attach containers streams to a
websocket. When a websocket is asked the request is upgraded to this
protocol..
put the websocket route in the map containing all routes

Instead of handling the websocket differently just handle it as a normal
route and upgrade it to a websocket.
useless type
useless function. forgot to remove it.
reuse the type
Implemented a Mocked version of the Registry server
Fixed mocked registry
Mocked registry: Added X-Docker-Size when fetching the layer
Disabled test server in the tests
registry: Fixed a bug where token and cookie info wouldn't be sent when using LookupRemoteImage(). Fixed a bug where no error would be reported when getting a non-200 status code in GetRemoteImageLayer()
Mock registry: Fixed a bug where the index validation path would return a 200 status code instead of the expected 204
New registry unit tests remade from scratch, using the mock registry
gofmt
Mock access logs don't show up in non-debug mode
Cleanup
Adapted tests to latest registry changes
Merge pull request #1364 from dotcloud/bump_0.5.1

Bump to v0.5.1
fixed #910. print user name to docker info output
Change daemon to listen on unix socket by default
fix the upstart script generated by get.docker.io (it was not starting dockerd on boot)