Embed taar-lite as a recommendation module

[crankycoder]

We want to be able to use taar-lite as a recommendation engine within TAAR's ensemble recommender.

This means:

• adapt taar-lite to be an ETL job to generate recommendation graphs
• generate a list of recommendation lists for each of the addons that are installed by a particular client

Merging the list of lists by weight should be relatively straightforward. Merging duplicate recommendations should more heavily weight those particular GUIDs but we have no predefined merge method yet.

[crankycoder]

merged in #176