Add cdnjs

https://github.com/yasuyk/cdnjs.el
Merge pull request #1500 from yasuyk/cdnjs

Add cdnjs
Add rdf-prefix recipe
Add elwm

https://github.com/Fuco1/elwm
Merge pull request #1497 from simenheg/master

Add rdf-prefix recipe
Merge pull request #1501 from yasuyk/elwm

Add elwm