ActiveResource Format extension method should contain '.'

Imported from Lighthouse. Original ticket at: http://rails.lighthouseapp.com/projects/8994/tickets/6583 Created by Axel Tetzlaff - 2011-03-15 16:54:58 UTC

I appreciate having the encoding strategy in the dedicated Format modules. Unfortunately is the dot not part of the extension method, but hardcoded in the elem_path method. That leads to an unnecessary inflexibility.

see also:

http://stackoverflow.com/questions/767203/how-to-remove-xml-and-json-from-url-when-using-active-resource