Add Learning Record Store (LRS) support to Sakai

Add support for Sakai to work with LRS's. The goal here is to create an API which can use a variety of learning record implementations (possibly multiple ones at a time) which will allow for future implementations and also can allow tools and other stuff in Sakai to register LRS activities in a centralized way.

http://en.wikipedia.org/wiki/Learning_Record_Store
A Learning Record Store (LRS) is a data store that serve as a repository for learning records necessary for using the Tin Can API.[1] The Tin Can API is also known as "next-gen SCORM" and the "Experience API".[1] The concept of the LRS was introduced to the e-learning industry in 2011, and is a shift to the way e-learning specifications function.

Learning Record Store (LRS) = a place to store learning records.
The concept of Learning Record Store (LRS) is a new one that goes hand in hand with the Tin Can API. The future of e-learning will require a repository (LRS) for learning records that can be accessed by an LMS or a reporting tool. It’s very likely that an LRS will be a component of an LMS.

Current XAPI spec (1.0.0 at the time of this work) is here:
https://github.com/adlnet/xAPI-Spec/blob/master/xAPI.md