Ignore changes to submodules, we update them anyhow in the install script.

This ignores changes to submodules, in the install script we just update them anyhow, so why keep having to update the versions in git.  Once again, it's a cherry pick that needs to be done.  I wish github had a better method of controlling this...

This just adds ignore = all to every submodule in .gitmodules if you want to add it that way.