Fix mixed statements and declarations, memory leak

Cleaned up mixed statements and declarations which offend
-Werror=declaration-after-statement (under python 3.4).

Also fixed memory leak in Async_dealloc().
Merge pull request #131 from ccstolley/libev_decl_fixes

Fix mixed statements and declarations, memory leak
Avoid registering exit cleanups multiple times
Move libev loop components into a class
Delay initialization of shared connection state

This makes it much simpler to avoid sharing connection state across multiple
processes.

Fixes PYTHON-60
Update changelog
Update debian dependencies for 2.0.x

Fixes #133
Add debian/control step to README-dev release steps

Relates to #133
Adding wait_other_notice=True for ccm
Better messages and docs for Read/WriteTimeouts
Fix memory leak when destroying libev connections

The IO objects held a reference to their LibevConnection instances
through the callback.  This reference cycle was preventing the
connection from being garbage collected.

Fixes #93
Minor tweak to Read/WriteTimeout error summaries
Ensure token map is rebuilt when nodes are removed
Release 2.0.2
Make version 2.0.2.post
Fix changelog typo
dict_factory docstring fix
docstring fix
Document exceptions moving from cassandra.decoder to cassandra.protocol
Merge pull request #136 from dizpers/patch-1

dict_factory docstring fix