Sash: save a hash

On top of @erniebrodeur original Sash work:

1. Addressed a number of Rubocop violations
2. Used transpec to bring RSpec syntax up to 3.0.x compliance
3. Fixed argument syntax to be Ruby 1.8.7 compliant
Again here, we have `Bini::Sash` -- I think this should be `Hashie::Sash`