Fix invocation of group update getter.
Wrap time.time() in a helper method, so that getting the current time can be mocked out in tests -- the builtin library logging uses time.time to print, so if it's mocked out, and logging enabled, then the mock fails from unexpected method calls via the logging library.  Mocking only the wrapper method means we can test what we mean, without complicated mocking rules.
Remove an obsolete print, in the test output.
Hide help text output from app_test when testing the app invocations.