Cleanup protobuf defintions

[markstory]

As we developed taskbroker we needed to make a few changes to the protobufs. Because of our backwards compatibilty tooling we are not able to make many small incremental breaking changes, and have been accruing deprecated attributes.

Before we go to production we should revise the protocol buffers for tasks and update both taskbroker and sentry

• Change int to uint feat(taskworker) Use uint instead of int sentry-protos#56
• Remove TaskActivation.deadline
• SetTaskStatusRequest.fetch_next