Check project ID when doing sync

[wonder-sk]

When doing project pull/push, we should check project info based on project's ID instead of project name, to make sure that we're do the right thing even if something happened to the project:

• project got renamed (or project was transferred to other workspace and we still have access to it) - we sync as usual, using the new project name when doing upload/download API calls
• project was deleted - if project info returns 404, we know it got deleted
• project access permission was removed from our user - if project info returns 403, we know there's permission problem

Note: some projects created/updated with an old version of MM plugin will not have project ID stored in the metadata - it would be good if we could handle those correctly as well (just hope that the project was not renamed / transferred).

Once #190 is implemented, it should be possible to add auto tests that will exercise that check.