bitbucket write to stderr on push
Really loving this tool, but I'm having an issue, that is only kind of an issue - after committing and writing notes, I then hit push and I always receive this error, but the thing is, it actually does push the file. Or it seems to be reflected in the online repo.

![screen shot 2016-02-04 at 12 06 21 pm](https://cloud.githubusercontent.com/assets/970304/12803691/45b48b30-cb38-11e5-8f53-df53ae2f9ebd.png)

ps. the blurred text is the repo and branch url. I'm using bitbucket, but I dont think that makes a difference, does it?

Info: Sketch 3.5.1 w/ latest sketchtool.
