Some changes to the isolated test fixture

Some changes to the isolated test fixture

 a.) Setup EDS_REGISTRY_MODULES to use the local cache-reaper module
 b.) Setup EDS_CAMEL_PROVIDER_DIR to use the local provider
 c.) Added "source_name" and use separate ESource uids between tests,
     each test in the suite uses a separate ESource name

Note that 'c' is a stop-gap solution to the problem of not being able to
properly shut-down the whole test D-Bus environment between tests, it should
be removed once we can address that problem.