Attempt at fixing #72 - claim may observe exceptions more than once

Conflicts:
	src/main/java/stormpot/bpool/BlazePool.java
	src/test/java/stormpot/PoolTest.java
Add a shutdown @After assertion to the PoolTests.
Redo the test for #72 - now actually recreates the scenario
Add more output to the FailurePrinterTestRule to aid debugging
Merge pull request #73 from chrisvest/bug/72

Bug/72