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)
In my mind, the CacheAccessException indicates that or places the Store in an unknown condition.  I'm open to suggestions but I don't know that there's anything one can assert about the Store in cases where a Store operation threw a CacheAccessException.