Upgraded yard gem.
Added ParamsValidator::Validator::Whitelist class

This commit also adds support for non module validators.
Renamed var
Implemented whitelist logic
Fixed broken spec
Added support default whitelist value
Renamed method
Don't delete hash entries
Added whitelist error message
Added class constructor to InvalidParamsException
Added whitelist section to readme
Only define a default whitelist value if present
Replaced call to send
Added expect block
Turned module validators into classes
Removed usage of constantize
Removed legacy conditional
Merge pull request #3 from mptre/whitelist-support

Added whitelist validator