Inform the client instance of the returned protocol version

Signed-off-by: Raul Gutierrez S <rgs@itevenworks.net>
Cleaned up the Zookeeper make targets to use the proper variables in the Makefile.
Took the deprecated testing harness client defaults out of the _get_client method. This eliminates a deprecation warning while executing tests.
Removed unneeded import.
Queue.get() no longer does get_children() and sorted() on every call
Fixed _children race in Queue._inner_get()
Unregistering atexit handlers after stop Sequential*
Python 2.x compatible
- Add section on contributing recipes, add maintainer/status information for
  existing recipes.
Merge pull request #186 from jordoncm/master

Eliminating deprecation warnings for tests built on the testing harness.
Merge pull request #182 from rgs1/save-returned-protocol-version-by-the-server

Inform the client instance of the returned protocol version
Merge pull request #190 from mdevaev/atexit-leak-fix

Unregistering atexit handlers after stop Sequential*
Add changelog for PR #190
Add contributing to the sphinx doc build.
Add note about lock being re-entrant per Issue #134.
- Calling a DataWatch or ChildrenWatch instance twice (decorator) now throws
  an exception as only a single function can be associated with a single
  watcher. Issue #154.
- Lock recipe was failing to use the client's sleep_func causing issues with
  gevent. Issue #150.
Merge pull request #177 from mdevaev/queue-get-optimization

Queue.get() no longer does get_children() and sorted() on every call
- Change gevent import to remove deprecation warning when newer gevent is
  used. PR #191, patch by Hiroaki Kawai.