Add SSH URLs to git resource

[avtobiff]

Enable git dependencies to have the form

ssh://user@host:port/path/repo.git

[joaohf]

Hi,

As a suggestion, maybe update this https://rebar3.org/docs/configuration/dependencies/#declaring-dependencies too. With a valid example using ssh://.. . (https://github.com/tsloughter/rebar3.org/edit/master/content/en/docs/configuration/dependencies.md)

[avtobiff]

Note that there is a discrepancy between the documentation
that states that this is working now, since
tsloughter/rebar3.org#137 was merged, and the actual code.