added textual content to describe technical implementation of Birdie
added figures and other minor cosmetic changes
updated Birdie glyphicon...
patched with config.include('pyramid_chameleon') for pyramid 1.5 compatibility
updated birdie_view to add figures on the homepage
added 'pyramid_chameleon' in the install_requires for compliance with pyramid 1.5
removed python3 explicit occurrences in the textual content
added a word on python <=3.2 (2.7+ branch included) in the install section