Make username optionnal in ssh publisher (FIX)

[maethor]

The patch submitted in #222 was not enough to fix the problem. This patch fix the forgotten line.

I apologize for the inconvenience. This one has been tested.

[pjakobsen]

Good to have the username option, but what about using SSH on non- standard ports, eg. ssh -p 7822. I've tried

opts: -r -e ssh -p 7822

but no luck there.

[pjakobsen]

Turns out you can rsync to non-standard point by simply putting quotes around the ssh command, as follows:

......
command: rsync
opts: -r -e "ssh -p 7822"

[llonchj]

Thanks @maethor Please fix the commit to the suggested self.username = getattr(settings, 'username', '') and, if possible write some unittest for the case to merge.