[STORM-492] Custom TEST-TIMEOUT-MS Definition should also be set simply in code

Custom test timeout with variable TEST-TIMEOUT-MS was being defined with System Environment Variable. This cause a problem that we can't define it on every test simply. System property is now being used to define custom TEST-TIMEOUT-MS variable value instead of system environment. This can be simply set before every test as;

System.setProperty("STORM_TEST_TIMEOUT_MS", "20000");