Big rework. Fixes many issues with Crumple's design.

WSGI:
+ Handler added to parse a URL and serve a corresponding page.
+ No more content-length restriction on incoming requests (should be handled by the web server).
+ Added a shortcut method for serving static files.
+ Multiple pages can now be stored in one module.

Templates:
+ Extension tags now use '/' instead of '.' to specify directories.
+ Rendering is slightly faster due to reduced string concatenation
+ Template directory automatically detected
+ Extension directory automatically detected

Extensions:
+ Multiple extensions can now be stored in one module.

Libraries:
+ Now a part of the system path, meaning any modules dropped in should work.