Bug 909622 - [B2G][Helix][messages][zhaotao]Sending mms with attachment(chinese name mp3) fail - r=julienw

- Replace all non standard word characters in filenames with a # while encoding SMIL
- Remove HTML escaping in preference for replacing unsafe chars with the #
- Add unit test to ensure that quotes are always escaped

(cherry picked from commit c6625624dec07e2c875c8f3019b512f5ed2d076e)

Conflicts:
	apps/sms/js/smil.js