Add shadowJar to create a fatjar

Also sets default gradlew invocation to test + jar + shadowJar

Added two TODOs:
- change main class name once we have a runner set up
- versioning

Change-Id: I06b24e4bbec5d04c25ced9564bcbbf99ebacc195
Bug: 153274685
Test: ./gradlew, then check artifacts in build/ directory
1 file changed