Avoid PHP Warning, if a TestCase has no UseSessionItem configured

[sebastianneubert]

This happens, if you switch off all UseSession items in a test case.

Build in a check, if the array has valid content or cast the given parameter to an array.

PHP Warning: Invalid argument supplied for foreach() in /livetest2/src/LiveTest/Config/Tags/TestSuite/UseSessions.php on line 13

[phmLabs]

Does this solve the problem?

#37