#127 genericize abstract StoreSPITest
 #127 fix incorrect getKeyType() calls
Merge pull request #129 from lorban/issue-127

Issue #127 StoreSPITest should use type parameters
more key/value type checks
added test for new key/value type checks. filled out SPI tests for
Store.computeXXX() methods
review comments:
- remove junit method calls in SPI test
- Allow CacheAccessException to occur w/o failing test
some more review comments