Added logging of GetTask() RPC completion for failed requests.
Changed start scripts to use concurrent mark/sweep GC for proto.

The proto frontend was pausing for long periods towards the end of
experiments running at higher load. This commit changes the
start_proto_frontend.sh script to use concurrent mark and sweep GC
for the proto frontend (just like we do for sparrow), and also adds
GC logging, in an attempt to fix the problem.
Switched to using TThreadPoolServer, which performs marginally better.
Deleted StateStore cruft and fixed compile errors in tests.

The tests still fail due to changes in various abstractions,
but they do now compile.

This commit deletes the StateStore and code associated with it
that was no longer functional.
Updated build script to always pull and build the latest sparrow version
Implemented Strict Priorities
Temp hack for user stuff