updated plug. refactor router/controller.

fixes #54.
first part of a major refactor in order to allow
sugar to track plug's latest versions easier.
leveraging the placid way of handling routers
and controllers (handlers) so that they are more
plug-oriented and can use plugs in a more
idiomatic way.
round two.

strip out hooks and filters in favor of plugs. plug stack in
controllers allows for before/after functionality, but router
stack doesn't. not sure that it needs it.
add functionality/tests for matched controller/action in
conn.private.
improved test coverage.
round three

fix copy_req_content_type router plug.
add HttpsOnly and XML parser
Merge pull request #56 from sugar-framework/feature/plug-refactor

Updated plug. Refactor Router/Controller.