elk_jquery_embed.js: add m.youtube.com handler
elk_jquery_embed.js: add m.youtube.com handler

See http://www.elkarte.net/community/index.php?topic=4633.0
StealthWombat/How-to-fork-an-Elk,Spuds/Elkarte,nwsw/Elkarte,StealthWombat/How-to-fork-an-Elk,interlab/Elkarte,elkarte/Elkarte,emanuele45/Dialogo,elkarte/Elkarte,emanuele45/Dialogo,StealthWombat/How-to-fork-an-Elk,Spuds/Elkarte,Spuds/Elkarte,StealthWombat/How-to-fork-an-Elk,interlab/Elkarte,elkarte/Elkarte,emanuele45/Dialogo,interlab/Elkarte,nwsw/Elkarte,nwsw/Elkarte