Make bootstrapThrift quiet.

Testing Done:
./gradlew build
./gradlew --info build

Reviewed at https://reviews.apache.org/r/24017/
Update to RBTools 0.6.2

Lots of improvements, including git workflow integration - see
https://www.reviewboard.org/docs/releasenotes/rbtools/0.6/

Testing Done:
./rbt post
./build-support/tools/list-missing-shipits

Reviewed at https://reviews.apache.org/r/24018/
Add a human-friendly HTTP/JSON API with auto-generated documentation.

Bugs closed: AURORA-369

Reviewed at https://reviews.apache.org/r/23741/