Limit formatting routes when adding resources

By default, routes.mapper.Mapper.resource adds a bunch of formatted
routes that accept anything after a '.'. Our spec says only .xml
and .json are accepted so limit the formatting to those valuse.

This allows identifiers with a '.' in urls. A few tests were added
to the extensions test to prove that .xml and .json are stripped
but other values are not.

Closes-bug: #1307956
Change-Id: I8f0b4ae3b10ea93890f6506662905bd5823412f5
Merge "Limit formatting routes when adding resources"