Issue #147 - Add non-bulk Ehcache unit tests

Adds unit tests for the following Ehcache methods:

* get
* put
* containsKey
* remove(key)
* clear
* iterator
* putIfAbsent
* remove(key, value)
* replace(key, value)
* replace(key, oldValue, newValue)
Each of the statements checks for a different, observable effect of the remove() call.  With the changes that have been made to Ehcache over time, I don't dare assume that a 'false' return will produce an RemoveOutcome.FAILURE or vis versa -- several of these have changed significantly while these tests were being constructed.