Test against Ruby 2.1.2.
Merge pull request #207 from boone/ruby212

Test against Ruby 2.1.2.
Show actual value in validation message for easier debugging
Merge pull request #208 from bolshakov/validation-message

Show actual value in validation message for easier debugging
Dedicated gemfiles and specs for Mongoid 3 and 4
Specs on mongoize with invalid currency
Merge pull request #209 from timstott/dedicated_gemfiles_and_specs_mongoid_3_and_4

Dedicated gemfiles and specs for Mongoid 3 and 4
Rescue from unknown currency errors on mongoization
Merge pull request #211 from timstott/mongoize_unknown_currency

Mongoize unknown currency