Port the ZeroRPC middleware to the new ZeroRPC middleware API
Don't hide the whole traceback on a PUSH/PULL or PUB/SUB ZeroRPC server

This changeset fixes the hide_zerorpc_frames option for the ZeroRPC
middleware. PUSH/PULL or PUB/SUB ZeroRPC servers were simply not
handled.

I'm also moving away from raven.utils.stacks.iter_traceback_frames
because the special variable __traceback_hide__ seems to stick across
exceptions and iter_traceback_frames doesn't return already hidden
frames.
Merge branch 'master' of git://github.com/getsentry/raven-python
Improve the ZeroRPC middleware docstrings a bit
Update compatible versions in the ZeroRPC middleware documentation
Merge pull request #237 from lopter/master

Update the ZeroRPC middleware for zerorpc-python >= 0.4.0