Remove python bindings unittests from the build.

Remove python bindings unittests from the build.

Instead add a run_mojo_python_bindings_tests.py that will be run from
the bots. This also refactor run_mojo_python_tests.py to factorize the
common code.

BUG=407818
Committed: https://crrev.com/b5d3236c107c3c1972657c2a832c379a8bd5b903
Cr-Commit-Position: refs/heads/master@{#292372}

[qsr, 2014-08-27 09:50:21]

qsr@chromium.org changed reviewers:
+ dpranke@chromium.org

[Dirk Pranke, 2014-08-28 00:32:02]

lgtm.

basically seems fine.

I'm hoping to eventually remove all of this code in favor of a generic python
test runner (see bug 402172), but there's no reason to block on that and no need
to sweat the details of the code sharing in the meantime either.

[qsr, 2014-08-28 08:26:17]

Thanks.

 Having a generic test runner would be great.

[qsr, 2014-08-28 08:26:19]

The CQ bit was checked by qsr@chromium.org

[commit-bot: I haz the power, 2014-08-28 08:27:13]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/qsr@chromium.org/509863002/1

[commit-bot: I haz the power, 2014-08-28 12:59:57]

Committed patchset #1 (id:1) as db59690977a81bcb2e287d494925db0d9659b3b5

[commit-bot: I haz the power, 2014-09-10 02:59:13]

Patchset 1 (id:??) landed as
https://crrev.com/b5d3236c107c3c1972657c2a832c379a8bd5b903
Cr-Commit-Position: refs/heads/master@{#292372}