Added some benchmark code for sessions

This will be a reference for optimizing our session middleware
JMS #38: Some major optimizations for the sessions middleware.

Sessions is still in a weird state. I will get it cleaned up and
have more tests. So far it is looking far better than it was
JMS #38: Formatting
JMS #38: Cleaned up benchmarks
JMS #38: Refactored a bit
JMS #38: Error handling for store.Get
JMS #38: Added flashes back. This time with tests
JMS #38: Formatting
Sketching out some ideas for yield implementation
Slight refactoring and made ErrorHandler a Martini handler itself. Closes #46.
Getting some render options going
Tests passing
Formatting
Formatting
Layouts with the yield function
Multiple extensions supported
Added Support for Funcs in render
Changed top level example
Added more godoc documentation
Update README.md