Jetty8

Closes Issue #13 

Updates Jetty from 6.1.26 to 8.1.8.v20121106 (the version that is bundled with Solr 4.3.1).

Adds a start.ini for passing in arguments to start.jar, which simplifies invocations.

jetty.xml is now stock, with customizations provided in etc/ and called from start.ini