Fix bug and unit test failure in HHWheelTimer

Summary: Some minor bug and a failed test caused by D1578466

Test Plan:
fbconfig thrift/lib/cpp/test:HHWheelTimerTest && fbmake
runtests

Reviewed By: davejwatson@fb.com

Subscribers: trunkagent, alandau, bmatheny, njormrod

FB internal diff: D1581949
CCmanager: Don't log err if default cc is MEMORY

Summary:
Credentials cache manager will not log errors every time it tries to
persist MEMORY ccache in file. Only one INFO message will be loged instead.

Test Plan:
1. Unit tests
2. Ran application with MEMORY ccache.

Reviewed By: andrei.bajenov@fb.com

Subscribers: trunkagent, alandau, bmatheny

FB internal diff: D1585399

Tasks: 5248806
Close connection on the server when client closes

Summary:
Before this diff, the server would only close a connection on
idle timeout. Now, the server will close also in case the client closed.

Test Plan:
Run a test client and server, watch tcpdump and
connectionDestroyed() event firing on server.

Reviewed By: haijunz@fb.com

Subscribers: trunkagent, alandau, bmatheny

FB internal diff: D1587753

Tasks: 5254405
Bump version to 11:0