Cleaning up avocado build.

Various build cleanup:

* Split the main Avocado class into a cli module. Long term, we'll move all config out of the core module and into the cli module (see #86). This resolves #31, at least for now.
* Changed version 0.0.2 to 0.0.2-SNAPSHOT, and renamed main project to avocado-parent.
* Refactored dependencies in parent project into dependencyManagement.