add apps factory and test it.
refine the docstring processing and add facebook, dropbox, github.
add more apps from the example source.
test linkedin and fix up the deep copy issue.
refine docs.
fix up the python 3.x compatible issue.
fix up the python 2.6 compatible issue.
Add contributor in code file:
https://github.com/lepture/flask-oauthlib/pull/94
Add @stianpr in author list
Changelog for 0.5.0. Version bump to 0.5.0
Fix documentation
Add Python 3.4 to classifiers
Update references to db.relationship in oauth2 docs

It is not apparent right away where `relationship` comes from. Ideally, we just prefix it with db like the rest of the model definition.