ISP-477 Post Java 7 upgrade cleanup and Prep for Jetty 8 upgrade

* Removing the animal sniffer plugin now that we're up on Java 7.  Don't need to slow *every* build down with that sanity check.

* Consolidating the version.java.source and version.java.target under just plain old "version.java".  We have no plans to cross-compile for a looooong time
* Adding jetty to dependencyManagement and jetty-maven-plugin to pluginManagement (centralizing Jetty version in opower-parent across pose-parent and archmage)