HystrixThreadPoolMetrics.getRollingCountThreadsExecuted() always returns 0 in 1.4.x - failing test case
Merge branch 'pr/339' into evaluate-pr-339

Conflicts:
	hystrix-core/src/main/java/com/netflix/hystrix/HystrixThreadPoolMetrics.java
Added back calls to threadPool.markThreadExecution() and .markThreadCompletion() in AbstractCommand
Merge pull request #367 from mattrjacobs/evaluate-pr-339

Added thread pool metrics back to execution flow