Remove getVersion RPC and DEPRECATEDversion Response field.

Bugs closed: AURORA-143, AURORA-467

Reviewed at https://reviews.apache.org/r/28623/
Collect HTTP stats on every request.

Reviewed at https://reviews.apache.org/r/28728/
Remove redundant storage.write.

Reviewed at https://reviews.apache.org/r/28725/
Drop custom thrift doc generator in favor of the one included in thrift.

Bugs closed: AURORA-947

Reviewed at https://reviews.apache.org/r/28682/
Remove Response.messageDEPRECATED field.

Bugs closed: AURORA-466

Reviewed at https://reviews.apache.org/r/28674/
Make abstract method annotations on ConfigurationPlugin effective.

Reviewed at https://reviews.apache.org/r/28693/
Remove unused DefaultServlet subclass.

Reviewed at https://reviews.apache.org/r/28738/