Preliminary work on etcd api v2, #8
minor refactor
Basic support for v2 with tests, #8
Bumped version to 2.0.0
Enables watcher to handle unexpected response.

The response data might not contain an index parameter for any reason, or even might not be an object. In that case the watcher would not recognize this and would not continue watching.
Added beta instructions to readme
Added test for PR #7
Updated readme with info about watcher error emit
Published v0.6.0
Updated readme for v2
Watch now uses v2 api
Added delete alias for del
All functions now use v2 api
Updated readme with better explanation of methods
Added testAndSet convenience method
Bumped to version 2.0.1
resp doesn't exist on an error
Added mkdir and rmdir
Updated watcher for etcd 0.2.0
compare and swap