Check that specified bundle is installed - must be called
before other methods that take a symbolicName parameter,
in case installBundle was just called and the actual
installation hasn't happened yet.
This is an evolution of the SlingTestBase/JarExecutor
combination that we had at revision 1201491, used
to control the server side of integration tests.
Runs all startup phases that have not run yet,
and throws an Exception or call Junit's fail()
method if one of them fails or failed in a
previous call of this method.