Fixes file serving.

* Added new example for file serving.
* Fixed logaccess reporting to cache initially requested method+url (stripprefix changed the URL)
* AccessLogger is now only added to each router once, instead of each handler
* ServeStatic() uses the internal routers instead of the net/http package.
Fixes example calls
Merge pull request #19 from catalyst-zero/fix-file-serving

Fix file serving