Allow ssh git links to be used.

[errm]

Links in the form of git@github.com:lsegal/yard.git
are now the default on github so it makes sense to
have the example in that format too.

Supporting SSH links makes running a private instance
nicer.

Mostly a duplication of #71 but drops the config
switch stuff in favour of just using the ssh format
everywhere.

[lsegal]

I don't mind supporting this, but I wouldn't recommend users use it. The git@github.com:... URL format only works when you have SSH keys with permission to access the repository, as opposed to the public format which allows anyone to access. Rubydoc would always prefer the public URL.

If you reverted the changes to the suggested URL / docs I can accept the other changes to the internal support.

As a sidenote, git@github syntax is not the default, at least not for me. GitHub seems to default to the https://github.com/foo/bar syntax.

[errm]

Ok, perhaps we should recommend the https syntax.
It looks like the default clone url is sticky on github if you are logged in so you see whatever you last chose, and if you are logged out you see the https url, so it should recommend that one.

It might be worth allowing the ssh urls for public repos as well, but it would mean creating a machine user on github and adding your deploy users public key.

On a private instance, with private repos the ssh url is the only option as the https one prompts for login.