New version with full text search

Hello, 

I've added extended search (and typeahead + highlighting) capabilities. You can now search for: 
- Feature
-- name
-- description
-- tags
- Scenario
-- name
-- description
-- tag
-- steps
-- table headers and table data rows
-- examples (for scenario outlines)
- Background
-- name (who have used that one? :))
-- description
-- table headers and data rows

Sadly I ran out of time (or rather: I've already spent way too much time on this and WAAAY too little on the book ...) so I have just made sure that the old tests work but I haven't added new tests. 
Sorry.