use relative protocol to load the reddit js

reddit breaks on https pages.
Merge pull request #1 from hermango/master

Merge pull request #9 from Course-Master/master
Merged trungpham's Reddit https loading fix
Merge branch 'master' of https://github.com/Course-Master/shareable into Course-Master-master

Conflicts:
	app/views/shareable/_reddit.html.erb
Trung Pham's fix for: reddit plugin does not work on https pages
Merge Trung Pham's fix for: reddit plugin does not work on https pages