decouple the builder classes from the model.  Builder objects should be
easier to reuse now.

`configure_dependency` actually defined callbacks, so rename the method
and move it to the appropriate method.

In some cases webservers like nginx send the escaped characters
lowercased to the Rails application. The current_page? helper was
comparing the escaped strings that are different since Ruby escapes the
URL using uppercased characters.

Fix status codes in document

Added missing closing bracket for markdown url in guides [ci skip]

RFC 6585 Additional HTTP Status Codes
http://www.ietf.org/rfc/rfc6585.txt

Moved README into action_view [ci skip]

This reverts commit 1468a4b8.

Refactor Date, Time, DateTime timezone methods

Similar implementations of #in_time_zone exists for Date, Time and DateTime so
method is extracted into its own module. Also some logic is extracted into
private method.