http tests and stuff:

* make GET to /put and /mput fail
* add basic HTTP tests and benchmark
Merge pull request #170 from mreiferson/http_tests

nsqd: http tests
learned a new trick
improve a flakey test (100ms is the resolution for channel workers)
nsqd: remove locks on topic messagePump()
nsqd: dont dupe msg for the first channel
nsqd: put clientv2 ticker on instance to avoid goroutine start race
nsqd: cleanup topic/channel exitFlag
nsqd: reduce garbage shown in escape analysis
nsqd: no copy message ids
nsqd: disable logging in V2MultiSub benchmark
simplify test message creation
update README benchmarks