Added node tagging feature in extensions/tagging.py
refactored tagging to use wallaby_mixin.py; added wallaby_collections mixin
added Store#addTag and Store#isTag mixin methods.
reorganized python client
updated ruby README
Merge remote-tracking branch 'classic-client/python-extensions' into feature/pythonclient
Infrastructure for Wallaroo python client.

Basically a fairly clean port of the Ruby client.  Uses the requests
HTTP library and some slightly nicer Python metaprogramming nonsense
than the Wallaby-classic library.

Includes a bare-bones node client that more or less works
as advertised.
ignoring .pyc files
errors.py à la Ruby client/wallaby-classic

example usage:

  import errors
  from errors import fail

  fail(errors.make(errors.NOT_IMPLEMENTED), "This command is not implemented")
first pass at python arc utils
minor bugfix in Proxy#update
Improved proxied-attribute handling.
added errors.not_implemented
Added ConnectionMeta#fetch_json_resource
Improved arc_utils interface
improved node proxy
found a stray ruby client bug
removed whitespace
proxied feature entity
found another stray ruby client bug