review /snsapi/third

[hupili]

When initialized, we want to make this project clone and play, so some third party modules are put in snsapi/third directly. Now that we inevitably depend on other modules, we can remove those files and:

• use requirements.txt if they are already in pypi.
• use git submodule
• If the module is not in pypi and not controlled by Git, we can mirror to Xsns and then git submodule it.

[hupili]

Also change obsolete modules:

• python-oauth2 is idle for a long time. https://github.com/simplegeo/python-oauth2/ . Use oauthlib, https://github.com/idan/oauthlib and one client implementation based on it, requests-oauth, https://github.com/requests/requests-oauthlib