Proposed patch converts test.test_support into package and rename it to test.support, move test.script_helper into the test.support package.  Old names test.test_support and test.script_helper are left as aliases to test.support and test.support.script_helper for compatibility (hence most tests don't need modification).

Benefits of this change:

1. This makes the structure of the test directory more compatible with 3.x. This helps bacporting tests. There were a number of cases when the only required change in backported 2.7 patch was changing "support" to "test_support". Many times backporting simple tests broke 2.7 buildbots because this change was not made.

2. This makes easier backporting changes in test.support itself and backporting 3.x features from test.support.