Adds support for non-git usernames in stringified url

[cbargren]

This will use whatever username is specified for ssh urls instead of the hardcoded git value.

import GitUrlParse from 'git-url-parse';

const url = GitUrlParse('ssh://myuser@mygitserver.com/owner/repo.git');
GitUrlParse.stringify(url); // 'git@mygitserver.com:owner/repo.git' <-- wrong username

// With change
GitUrlParse.stringify(url); // 'myuser@mygitserver.com:owner/repo.git'

I also added a change that will allow multiple protocols (ssh+git) to be stringified properly even if the type isn't specified in the method call.

[IonicaBizau]

That looks good! 👍