tests: added new test modules to cheshire3.test.__all__

- testIndex
- testLogger
- testResultSet
- testResultSetStore
- testUtils
tests: added trivial tests for Workflows
bugfix: fixed IndexError when Workflows log a zero-length message

e.g. <log></log>
tests: refactored testBaseStore

Generic test methods moved from BdbStoreTestCase to SimpleStoreTestCase
tests: added tests for store.clear()
bugfix: baseStore.clear() AttributeError _verifyDatabase -> _verifyDb

fixes #63