Escape message

mw.msg() should get escaped.

Restore jQuery code from before
I60a4b702a653d9b4b1d83ae2d83d4bc66ca9830f
for creating element. See:
https://www.mediawiki.org/wiki/Manual:Coding_conventions/JavaScript#Creating_elements

Change-Id: Icecd041dd3c2e28ff89e51d5128c7a15789530f4
Follows-Up: I60a4b702a653d9b4b1d83ae2d83d4bc66ca9830f
Merge "Escape message"