when no input is given, jump to the most frequent location

This replicates a feature of the original autojump that I use a lot.

I'm a complete C# noob, so the implementation is probably sub-par, but it should not be difficult to fix.
Add unit test GUID to Specs project
Add unit test for empty query. Replace query with one empty term by empty query on top level
Fix issue 7: Brackets doesn't escapes correctly after tab complition
Add Build from source section to Readme