Update rpx_now 0.7.0 and general packaging update

Main purpose here is to update rpx_now dependency to 0.7.0 (why? see https://github.com/grosser/rpx_now/pull/21)

In doing so I've also wrapped up a number of changes here from a few branches and hopefully left things cleaner.
* rolls in the schema.rb "final solution" and forced devise 2+
* dependencies all updated in the gemspec (removed jeweler since no longer really needed)
* pulls in the :request_keys support from Rick Martinez
* rakefile cleaned up
* fixed some specs

RSpec is clean and green! So hopefully a good base now for rolling other branches and changes. But note: I haven't checked test coverage.

NB: this pull request should effectively address \#19 too