Add Search Studies object

This object has natural language parsing for searches and returns a dictionary of {study_id: [samp1, samp2, ...]} of samples and studies matching the search query. An example query is also in the documentation, showing you can get pretty complex with them.
sorry, [this is a better reference](http://www.postgresql.org/docs/9.0/static/functions-matching.html), and we could also permit a regex to be passed for more robust INCLUDES statements (although I'm not sure about security concerns, if any)