update code.jquery.com to https

[OmgImAlexis]

Since there's so many files in this I'm going to do multiple PRs.
These are mass updates using find and replace, I do check the domains before doing this.

http://code.jquery.com was replaced with https://code.jquery.com.

[jaspermdegroot]

@OmgImAlexis

First of all, thanks for the PR!
I don't think we should make changes in demos after they have been released, even if it's an improvement. The demos are also included in the ZIP-file of each release and those should be identical to the ones we publish on our web site.
@arschmitz what do you think?

[OmgImAlexis]

@jaspermdegroot why not just force code.jquery.com and all other domains to force a http -> https redirect and enable HSTS? I've noticed there's no force redirect for a lot of your domains as I can still use curl or wget to access the http version and HSTS would mean browsers would know to only allow https. You guys might also want to look into adding the jquery domains to https://hstspreload.appspot.com/ so major browsers never allow http versions to be loaded.