Assorted cleanups

Hello @dpup, 

Please review the following commits I made in branch 'vinny-cleanups'.

6c16eccf41bb9c136b3551109c85588cf9c4bd5c (2013-05-28 20:44:18 -0700)
Move the rendering method to the template renderer

a03919706cfeb12ec6d2d421b5636123f2a0e4a5 (2013-05-28 20:20:43 -0700)
Moving template engine code to a new class

e95639125e33dfe36d7229b20f911561ba34482d (2013-05-28 19:36:15 -0700)
Adding tests for before filters, small cleanups

c09dd648e7c1c79279eafbdff8a0087fc4ca3dea (2013-05-28 19:19:27 -0700)
Adding test for response.redirect() decorator 

R=@dpup