Apply PEP8
Don't call `_config_nodes` when another `_config_nodes` is in progress
If we call `get_node` twice before starting IOLoop, `_config_nodes` will be called twice, and therefore subsequent `_config_nodes` will be called twice every 30-seconds.
Fix wrong assumption about synchronous error while connecting to an unavailable node
Merge branch 'tahajahangir-add-travis'
Merge branch 'patches' of https://github.com/tahajahangir/mongotor into tahajahangir-patches
Merge branch 'tahajahangir-patches'
Merge branch 'pr/44'
Merge remote-tracking branch 'marcelnicolay/master' into coroutine-py3
Fix wrong tests / use gen.coroutine in tests
Add python 2.6/3.2/3.3/3.4/pypy to travis
Compatible with new version of sure
Use new except syntax (Python 2.6+/3.x)

Conflicts:
	mongotor/node.py
Use Exceptions as errors base class (instead of StandardError)
Use six to compatible with python 2,3
Use string literals instead of unicode
Use unittest instead of sure
No need to run 2to3.py (Code is compatible using six)
stop testing on python 2.6/pypy for now