Priority of the delayed actions in CurrentThreadScheduler
CurrentThreadScheduler updates.

Unit test that mixes delayed and immediate scheduling.
Added counter to resolve conflicts in case in time between enqueueing took less than 1 ms.
Merge branch 'master' into sched-priorityqueue

Conflicts:
	rxjava-core/src/main/java/rx/concurrency/SleepingAction.java
Merge pull request #239 from mairbek/sched-priorityqueue

CurrentThreadScheduler Delayed Execution Fix