Added a new extension for oauth2 providers that integrates with flask.

Modified the existing scopes argument for django provider so that it now will
accept a function as well as a list object. This is done so that scopes can be dynamically
set.
Small modification so that the dynamnic scopes now will pass the requests object in django.
Updated the documentation for dynamic scopes.
Fixed a small error with the flask extension.
Fix swapped values in example of Django choices
Removed the use of the flask g object from the extension, the properties can now be pulled from the OAuth2ProviderDecorator
Merge pull request #151 from stephane/docs-django-choices

Fix swapped values in example of Django choices
Merge pull request #148 from flippmoke/master

Flask OAuth2 Provider and Dynamic Scopes
The argument request is missing in validate_code() in examples
Fix documentation warnings
Missing required arguments in authorize()
Wrap and trailing whitespaces in README.rst
Fix extracting of scope values from POST

Many inputs with same name are stored in a list.
Merge pull request #157 from stephane/missing-args

Small fixes related to OAuth2 and Django example
add more python version in travis and tox. #73
remove unittest2, since it brokes on py3
Add optional expires_in parameter to BearerToken

The expires_in is still 3600 by default.
only install unittest2 on python 2.6 and 2.7
add coveralls
Add token_expires_in opt to all-in-one endpoints

It still works as it has worked until use the option.