Fix param with period not work

[ningt]

Refer to Issue 5

@jacwright

[baskettcase]

This wasn't added in? I had to manually make the changes.. would be great to have this in master.

[tyzoid]

The main issue is that this is how the output format is defined, for ex:

/api/endpoint.json => returns a json object
/api/endpoint.xml  => returns an xml object

This could be solved by changing the way that the format string is handled, but requires careful attention. As is, this PR would essentially break this functionality.