Batchy

Features:
- Contexts: coroutine-propagating locals. These work correctly in the presence of context-switching yields.
- Added batchy.coroutine: a shorthand for the "default" decorator to use on batchy functions; in case we ever need to change it.
- Please migrate to this if you're using batchy! Coroutine-locals don't work correctly with the old runloop_coroutine decorator.
- Add ability to use gevent in the redis client - to parallelize io.
- Better support more pylibmc features (unfortunately just support; they are not batched)
- Add wait function which waits for k/n batchy futures (or deferreds, but you should never see those).
- Support `return` in py3.
- Add support to explicitly switch the thread-local implementation - greenlets and threads are available.
- Support for using waiting on concurrent.futures .

Bugfixes:
- coverage reports work better locally.
- even earlier yelling about functions not returning generators.

Features:
- Python 3 support. The next release will support using the regular `return` statement in python 3.
- Add runloop_memoized_coroutine, rmap and rfilter (in batchy.util).
- Create a common RunLoopLocal class.
- Tox testing config & integration with Travis.

Bugfixes:
- tests.py now correctly returns a non-zero exit code when the tests fail.
- yielding non-generators/deferreds now raises errors a lot earlier (with a root cause)

Initial release