Removed MutexPool, we don't have to be compatible with go1.2 anymore

The ByteSlicePool will now always use sync.Pool, this bumps us to
require go1.3+

Adjusted RingBuffer type to fit new pool handling and added documentation
Added logging to a lot of error paths, other small changes.

Fixed not calling Flush on the bufio.Writer in SourceHandler

Switched to using a small utility function around http.ReadRequest in
MetadataHandler and ClientHandler. This function adds RemoteAddr currently.

Fixed MetadataHandler wrongly using the request path rather than the mount
query value as mount name.

Fixed MetadataHandler not writing the expected xml response to updaters

Fixed MountExists to lock the mutex before touching the mounts map

Added Host field to SourceID and proper filling of the new field in NewSourceID

Switched to HTTP/1.0 in WriteHeader