Sometimes, SMARTS return a TypeError for the TestResults

[MiCurry]

Traceback (most recent call last):
  File "/glade/u/home/mcurry/SMARTS2/smarts.py", line 251, in <module>
    args.func(args)
  File "/glade/u/home/mcurry/SMARTS2/smarts.py", line 149, in run_cmd
    test_handler.run_tests(tests, env)
  File "/glade/u/home/mcurry/SMARTS2/smarts/testManager.py", line 511, in run_tests
    ' - "'+test.result.msg+'"\n')
TypeError: can only concatenate str (not "NoneType") to str

I belive this happens when a test fails and does not set result.msg. We just need to handle concatinating NoneType. Its okay if a tests result.msg is a NoneType, but it should not clobber the messages of other tests.