NEW: Create jar that prints out link and node relationship and serve file for download at /apk/:id endpoint
(WIP)NEW: Model Transformation

This commit includes the classes for ModelTransformation, and visual
model ‘App’ and ‘Screen’ node types. Also included are unit tests for
the above classes and some changes to the Application controller.
ENHANCED: Serve zipped project.

The resulting android project is zipped before serving it to the
client. Also fixed a dependency conflict which was being caused by an
old version of RAPT. Model transformer throws
ModelTransformationException instead of returning null when errors
occur.
ENHANCE: Navigation is now generated

Navigation for the given screens is generated (assumed navigation)
FIX: Nodes are using "id" not "nodeID"
FIX: "appProperties" -> "appPropertiesNode"
FIX: Path creation issue for zip files.
Merge branch 'feat/prototype2'