Multi project build

Partitioned EnMAS into several sub-projects, each versioned and deployed separately from here on out:
- enmas-core
- enmas-server
- enmas-client
- enmas-bundler
- enmas-examples

EnMAS now uses the sbt-assembly plugin to generate "fat" (including all dependencies) executable JAR binaries for the three application entry points (server, client, bundler).

EnMAS now uses the sbt-gpg plugin to digitally sign all build products.  This is required of artifacts that hope to eventually make it to Maven central.

The top level EnMAS build definition now publishes to a temporary maven2-style micro repository I set up at http://enmas.github.com/repo while we await publish rights to Sonatype OSS.  We should have access by roughly Tuesday, 12 Feb 2013.