Mute specs

Adding [`mute`](https://github.com/chrishunt/mute) to get rid of all the noise in the test suite:

```bash
Adding 2 key(s) to '/var/folders/h1/7p4l5pbj1bjf_2v4c1mvh04r0000gn/T/authorized_keys20140119-77857-iyqam2'
Removing 2 key(s) from '/var/folders/h1/7p4l5pbj1bjf_2v4c1mvh04r0000gn/T/authorized_keys20140119-77857-iyqam2'
.Adding 2 key(s) to '/var/folders/h1/7p4l5pbj1bjf_2v4c1mvh04r0000gn/T/authorized_keys20140119-77857-10b5b6o'
Removing 2 key(s) from '/var/folders/h1/7p4l5pbj1bjf_2v4c1mvh04r0000gn/T/authorized_keys20140119-77857-10b5b6o'
.Adding 2 key(s) to '/var/folders/h1/7p4l5pbj1bjf_2v4c1mvh04r0000gn/T/authorized_keys20140119-77857-q4330y'
.............................................
```