media: add Media#del() alias to #delete()
media: add Media#del() alias to #delete()

the .del() version should be the version used in docs, etc. though
since it will have better JavaScript environment support.

dnessorga/wpcom.js,DNESS/wpcom.js,Automattic/wpcom.js,Automattic/wpcom.js,DNESS/wpcom.js,dnessorga/wpcom.js