ISPN-4651 LevelDB crashes JVM when stop() is called concurrently with write()
ISPN-3979 JdbcStringBasedStore loading of Key2StringMapper class is too
restrictive

* Key2StringMapper class is now loaded using ClassLoader from
* GlobalConfiguration
ISPN-4649 RemoveCommand does not activate the key in Passivation

* No tests added since ISPN-4559 tests cover this scenario
ISPN-4559 Replace fails with cache loader

* Tests all the conditional commands
ISPN-4657 Allow for customization of SearchWorkCreator used by the QueryInterceptor
ISPN-4446 Signal components of cache removal

* Since stop() takes no parameters, make the remove cache command
signal components of cache removal before cache stop, so that they can
do their job.