Added lucene store decorator

I noticed some talk around full-text search #73 so I decided to have a go at writing a simple lucene wrapper which should work in conjunction with any biggy store allowing you to get some lucene luvin' action.

I did have to change the BiggyList interface and I wasn't sure the best way to do this so I created a SearchableBiggyList which takes a simple string query, which I guess should work for most search interfaces?

The tests should give you an idea on how it works, there are a couple of things I need to look, paging and handing updates (IUpdateableBiggyStore) for now I'd be interested in hearing what you guys think.