Allow :format option lookup via I18n or DATE_FORMATS hashes

First attempts to find the passed in `:format` option in:
1. I18n `time.formats.{format}`
2. I18n `date.formats.{format}`
3. `Time::DATE_FORMATS`
4. `Date::DATE_FORMATS`

Else, returns the passed in `:format` option straight up or, if blank, uses the
default format: `%B %e, %Y %l:%M%P`.