Replace secret initializer with secrets.yml

This is the preferred way of doing things in 4.1
Update installed Spring binary
Remove "ruby-" prefix from .ruby-version

It is not needed.
Remove .ruby-gemset file for switch to rbenv
Update Travis Ruby version to 2.2.0
Update Ruby to 2.2.0
Update gems
Regenerate schema using updated gems
"Secret" keys for dev and test
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.
Merge branch 'rails-4.2'

* rails-4.2:
  Exempt `couple_round_tallies` from database clean
  Convert `couple_round_tallies` to non-schema_plus
  Remove schema_plus gem and convert migrations.
  `serve_static_assets` to `serve_static_files`
  Use random test order.
  Update to Rails 4.2