[split] Fix build failure

RB_ID=196375
[split] release finagle 6.7.1

The release of Finagle 6.7.0 failed midway through due to tooling
issues [1], leaving artifacts published for some subprojects but not
others. We're rolling forward with a 6.7.1 release.

[1] https://reviewboard.twitter.biz/r/205208/[INFO] finagle-benchmark

RB_ID=205426
TBR=true
[split] finagle-core: removes commented out casting filter

RB_ID=205248
[split] finagle-mysql: move protocol into a dispatcher and port to new style apis.

RB_ID=187441
[split] use scrooge3 to compile finagle-exception and finagle-zipkin with sbt

RB_ID=207786
[split] finagle-core: added a simple defaultpool test to show how it works + more docs

RB_ID=205198
[split] Improve GC profile of Var and Group With the current implementation of Var, calling apply() allocates a couple of objects and increments the version variable. This causes some GC problems, and will violate the observer ordering guarantee when the version integer rolls over.

RB_ID=202893
[split] LoadService: skip empty lines

RB_ID=208378
[split] birdpants: fixing 3rdparty tree references

RB_ID=195557
TBR=true
[split] Tagging finagle-stream test as flaky

RB_ID=208744
[split] Finagle 6.7.2 release

RB_ID=209638
[split] finagle-core: Fail the queue before closing the connection

RB_ID=173739
[split] bump finagle to 6.7.4-SNAPSHOT

RB_ID=210176
[split] bump scrooge to 3.9.3-SNAPSHOT

RB_ID=210574
TBR=true
[split] bump scrooge to version 3.10.0-SNAPSHOT

RB_ID=210718
TBR=true
[split] bump sbt versions for build

RB_ID=210586
TBR=true
[split] finagle-doc: nits, make sure finagle version number propagates to sphinx

RB_ID=210892
[split] finagle-zipkin: depend on scrooge-core instead of scrooge-runtime

RB_ID=211280
TBR=true
[split] eventbus: subscriber worker threads shouldn't Await.ready

* eventbus/client/IterableThreadPoolEventBusSubscriber.scala:
    Simplified event loop:
      *Don't* await for the result of service().  A thread is used
	to start event processing, but finishes before processing
	is finished.
      Use a FuturePool instead of raw ExecutorService
      Concurrency limit is still enforced.
      Futures are no longer canceled on close().

* eventbus/client/IterableThreadPoolEventBusSubscriberSpec.scala:
    Remove test for canceling futures - this is no longer supported

* finagle/finagle-core/InMemoryStatsReceiver.scala:
    synchronize ReadableCounter.incr and ReadableCounter.stat

RB_ID=206270
[split] [finagle-mux] Adds Session for mux message passing and bidirectional RPC

RB_ID=187527