nest lost rake tasks together

Added nested namespace for lost rake tasks. 

Also change lost:db:reset rake task to simply drop *lost* table rather than resetting the whole db. I think this is desirable since we plan to have multiple tables/workflows in the app.
One issue with the commit is that the index is not reset; when the *lost* db is refreshed, the ID count increments from last record number (rather than zero).

There is an approach to extend active record base class with a method to reset the id but I've never changed rails built-ins, wondering what you think:
http://stackoverflow.com/questions/2097052/rails-way-to-reset-seed-on-id-field

Resolves #28