Add Spanish translations

using span with css instead of img

using span instead of img to avoid problems with relative paths

Added italian translation

Fixed compare operator in strophe.muc. (Thanks!)

Conflicts:
	locale/hu/LC_MESSAGES/converse.po

Even though they are actually not used directly and instead a step between the
PO file and generating the .js file

Trying to make it simpler and easier for people to add new translations by
reducing the amount of places where edits need to be made (e.g. no new edits
required in converse.js now).