Merge branch 'update-rails'

* update-rails:
  "Secret" keys for dev and test
  Regenerate schema using updated gems
  Update gems
  Update Ruby to 2.2.0
  Update Travis Ruby version to 2.2.0
  Remove .ruby-gemset file for switch to rbenv
  Remove "ruby-" prefix from .ruby-version
  Update installed Spring binary
  Replace secret initializer with secrets.yml
Update to Rails 4.2
Use random test order.
`serve_static_assets` to `serve_static_files`
Remove schema_plus gem and convert migrations.
Convert `couple_round_tallies` to non-schema_plus

Also, since Rails schema cannot dump views without schema_plus, the view
creation is contained in the db/structure.sql file.
Exempt `couple_round_tallies` from database clean

Not sure why this didn't cause trouble before, but now this is
necessary.