When using the waf tools in a stand-alone project the git protocol will
default to git@.

This change adds an option to specify the git protocol, when a
different protocol is appropriate.
Merge pull request #8 from steinwurf/allow-git-protocol-specifier

Allow git protocol to be specified.
Merge remote-tracking branch 'remotes/origin/master' into check-min-version
include git protocol option