Moved README into action_view [ci skip]
Added missing closing bracket for markdown url in guides [ci skip]
Fix status code in documents [ci skip]

RFC 6585 Additional HTTP Status Codes
http://www.ietf.org/rfc/rfc6585.txt
Fix `current_page?` when the URL contains escaped characters

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.
Add "extname" option to javascript_include_tag

ActionView::Helpers.asset_path is where the logic for
javascript_include_tag resides.  It takes an extname option for
specifying the extension or false to not append it.  This exposes that
option to javascript_include_tag.

Without the option files that didn't end with ".js" would get the
extension appended to them.  This broke JST templates and other file
types that should be interpreted as JavaScript but who's file extension
isn't ".js"