Catch up to v1.1.0 of beego

I've also tweaked the session backend for AppEngine a bit as well as updated the readme documentation for both the main package and the session's package. There is also the addition of the `appengine.Context` object on the default controller.

I've also removed packages that were not used and/or not compatible with beegae (e.g. context required no specialization so we can pull directly from beego. logs was not used and not compatible with AppEngine.)

I've done basic test working with memcache and trying out the sessions backend. A second set of eyes on the code changes would be highly appreciated!