Use a modern dependency management system

[tmagrino]

Currently we're manually managing jar dependencies in the lib folder and this can be a pain. I suggest we move to a more modern system for managing at least the dependencies for fabric, such as Ivy, Maven, or Gradle.

Ideally we could also support some custom build tasks/archetypes for a build system like Maven or Gradle to make it easier to set up and manage new Fabric and FabIL projects.