Add maven wrapper to avoid host maven requirement

[headius]

Requiring a host to have Maven installed is sometimes onerous, such as on systems that only contain a JDK for running applications. In my case, I would like to set up a Ruby gem that builds and installs honest-profiler for JRuby users, most of whom will not have Maven installed locally.

The Maven wrapper included here handles downloading a Maven install to a user directory and then proceeding with the build. No local Maven install is needed.