Use HTTPS for submodules
Use HTTPS for submodules

Travis has trouble fetching submodules with git URLs:

$ git submodule update
Cloning into 'examples/xsd-validator'...
Warning: Permanently added the RSA host key for IP address '192.30.252.128' to the list of known hosts.
Permission denied (publickey).

GeoscienceAustralia/GeodesyMLConverter,GeoscienceAustralia/GeodesyMLConverter