ISPN-4520 JdbcBinaryStoreTest.testLoadAndStoreWithLifespanAndIdle random...

* Use a custom TimeService to trigger the expiration
* refactor the BaseStoreTest (remove assert, fix indentation, remove duplicated code, etc...)
* clear the cache during stop for BaseStoreFunctionalTest (it was leaking the data in osgi environment)

https://issues.jboss.org/browse/ISPN-4520
currentNanos perhaps?