Fixed servlet/jstl/el/jsp support

Support for the JSTL was essentially broken previously. I tried to
upgrade to Jasper 7.x so that I could use the servlet 3.0 spec, but
Winstone only supports servlet-api version 2.5.
Fixed web.xml servlet version
Added Velocity template merging logic.

Added the ability to merge a simple Velocity template from the landing
page.
Updated the readme with instructions.