Switch to HTTPS locations so everyone can access them

When loading yasmate's submodules, I got an authentication error when trying to fetch `git@github.com:textmate/objective-c.tmbundle.git`. 

Now, I'm fairly new to all this and adding my SSH keys to GitHub (which I hadn't done yet) solved the problem, but I'm guessing that in order to be able to fetch via SSH, you need to have it set up with Github (i.e. have a Github account and have added your SSH keys to your account). 

So wouldn't it be better to just use HTTPS to load `objective-c.tmbundle`, so all of this preparation isn't necessary and everyone can access this?