Riak 1.4 protobuf support.

 - This pulls in all new messages.
 - This includes the Search and 2i messages.
 - Regenerated code for all messages, and updated cabal file.
 - Tweaked proto.sh script to not rely on hg.
 - Added exposed-modules.sh to generate list of modules for cabal file.
 - Added gitignore.
 - Update the riak client to compile with new fields.
 - Update test to abide null bucket/key constraint.

Tested with 1.4.1, 1.3.2 and 1.2.1.
Merge branch 'markhibberd/protobuf-upgrade'

Merges janrain/riak-haskell-client#19.

See #2.
Version bumps for new protobufs.