Autolinking non-http protocols doesn't work

If you redefined the AUTO_LINK_RE to support protocols other than HTTP, bad links are generated. In the auto_link_urls code it checks if there is an http in the generated href and if there isn’t it prepends one. If you’re using auto_link_urls on, for example, ftp:// links, instead of , you get This patch adds a test and changes the code to check for any protocol instead of just http before prepending the default.

This patch is against the 2-3-stable branch.

Lighthouse ticket:

-Zach Brock