pgit.sh has ssh://$login@git.janware.com/srv/git/$fromuser/proj/$reponame
hard-coded as the remote Git URLs of every cloned project.
This commit adds support for the global option --remote-base. Passing
it changes the URL to <remote-base>/$fromuser/$reponame..
Signed-off-by: Jan Lindemann <jan@janware.com>