Removed error log on playback start exception.
Replaced assertException with assertRaises in WordsTest.
Replaced assertException with assertRaises in VectorTest.
Replaced assertException with assertRaises in PythonTest.
Replaced assertException with assertRaises in PlayerTest.
Replaced assertException with assertRaises in OffscreenTest.
Replaced assertException with assertRaises in several more tests.
Replaced assertException with assertRaises in EventTest.
Replaced assertException with assertRaises in DynamicsTest.
Replaced assertException with assertRaises in AVTest.
Replacedi all remaining assertException cases with assertRaises.
Removed AVGTestCase.assertException.
Merge pull request #525 from libavg/bugfixes/assertRaises

Replace assertException with assertRaises in tests. Fixes #409