Initial proposal to differentiate sam only and sat only tests

Now tests can use decorators to run/skip tests basead on server modes:
- runIf('sam') - runs only on sam server
- runIf('sat') - runs only on sat server
- no decoractor - runs on all server modes
This can be turned into a module-wide constant.

    SERVER_MODES = ('sat', 'sam')

You can then do stuff like this:

    if project not in SERVER_MODES:
        raise ProjectModeError('...'.format(project, SERVER_MODES))