Check in some scripts I use for building and testing against multiple versions of Python
Add build to TestCommand's sub_commands

... and run the sub_commands in TestCommand.run. So if python setup.py test is
executed before ever running the build target, the extension modules are built.

Bug: https://bugs.launchpad.net/pycrypto/+bug/1055256
Bug: https://bugs.launchpad.net/pycrypto/+bug/976171
Use os.chmod instead of os.system("chmod ...")