re-organize imports/files
reader/writer: evented refactoring

* proper separation of responsibility, introduce Client
  superclass, move work into AsyncConn, etc.
* add EventedMixin to provide on(), off(), trigger()
* switch Reader/Writer
travis no longer supports python2.5
Merge pull request #52 from mreiferson/refactor_52

refactor
reader: add output buffering feature negotiation
Merge pull request #49 from mreiferson/ob_49

support output buffering feature negotiation
Added class attribute documentation for 'Message'.
Merge pull request #55 from dsoprea/master

Added object attribute documentation.
event doc updates
pep8
Merge pull request #53 from mreiferson/pep8_53

pep8
bump 0.6.0-alpha
add license
Add channel sampling support
Merge pull request #57 from elubow/sampling

Add channel sampling support
add an example client, nsq_to_nsq.py
fix travis
Merge pull request #60 from mreiferson/fix_travis_60

fix travis
moving module version into separate file
adding user_agent string to IDENTIFY