Allow multiple parameters for required_if
Merge pull request #4011 from alprs/feature/required-if-multi

Allow multiple parameters for required_if
Add space between lines of code.
Convert Mailgun and Mandrill drivers to Guzzle 4.
Remove unneeded accessor.
Fix posting of messages.
Added some irregular Plural
Merge pull request #4031 from abhimanyusharma003/patch-1

Added some irregular plural