Adding a class attr to attr_encrypted so AR MultiParamter works

see: http://stackoverflow.com/questions/17482507/correct-way-to-handle-multiparameter-attributes-corresponding-to-virtual-attribu
Merge branch 'ar-multiparameter'

* ar-multiparameter:
  Adding a class attr to attr_encrypted so AR MultiParamter works
Merge branch 'ar-preserve-hashes'

* ar-preserve-hashes:
  ActiveRecord adapter no longer forces hashes to be string-keyed
  Fix mass assignment protection in Rails 4
  whitespace
  Add pry-debugger
  Remove superfluous specification
  Fix bundler warning
DRY
Add new option: `allow_empty`

This option allows encryption of empty strings. It almost certainly
requires a custom encryptor.
Merge branch 'encrypt-empty-too'

* encrypt-empty-too:
  Add new option: `allow_empty`
  DRY