OK,DECLINED,FAIL scheme

added check.test in examples/monitoring; not tested yet

Revert "check.test"; had an misunstanding on it

This reverts commit a351c9f37d320f62a724125233552c5035040ea1.

better memory management: less new() -> less pressure on GC

Revert "better memory management: less new() -> less pressure on GC";
was a bug

This reverts commit 2091a51a54f3e527ec8c364d1a8203400e5fefe8.
added proactive comm, i.e., controller initiates rpc call.
added some test for proactive communication
fixed coding style to pass golint
added pre-commit hook for gofmt and golint