fix random threading problem in ConfigurationRegistryImpl

The old implementation used Job.getState to check if the loader has been
started. As getState is not thread safe, this caused random failures
(Exception: The configurations are not loaded yet.) when running the
test suite. 

Change-Id: I6b0c475117e52619e643ded9b5d3459dd09acae9
Signed-off-by: Carsten Hiesserich <carsten.hie@gmail.com>
4 files changed