Ticket #190 (friendlier way to add / register a mime type)

[Stephen Caudill]

Following up on #190 [1], I've just added a simple patch that allows  
the manipulation of the TYPES hash from within the Merb module. Use  
like:

Merb.add_mime_type(:png,%w[image/png])
Merb.remove_mime_type(:png)

It specifically disallows the removal of the :all MimeType, since  
content negotiation relies on it.

I'm not super wonderful at API design, so comments and suggestions,  
are of course welcome. If everyone likes it as-is, just shout and  
I'll commit it.

--

Stephen

[1] http://merb.devjavu.com/projects/merb/ticket/190