Default ssh command

I was trying to push some binary files (PNGs) over ssh and found some
files inexplicably wouldn't successfully push.

I set, in my .gitconfig file:

[core]
        sshCommand = ssh -e none

And it works now for all files (that I can tell).

From a close examination of the output where I noted escape codes
showing up, I believe the problem to be ssh escape codes.

`\n~.` for example closes the ssh client.

Therefore I think the default ssh command should be `ssh -e none`
instead of `ssh` for the benefit of users who won't recognize the
problem, unless `git` is expected to make use of ssh escape codes.

I'm new to the mailing list, sorry if I missed some protocol here.
Thank you so much for working on `git` and making your work
 available to the rest of the world. Cheers!