Bug 902070 - [email/activesync] Change jswbxml to run its unit tests under mocha. r=squib

upgrade jsas to take updated jswbxml; source pull requests are:
https://github.com/mozilla-b2g/jsas/pull/13
https://github.com/mozilla-b2g/jswbxml/pull/5
Merge pull request #236 from asutherland/update-wbxml-mocha

Bug 902070 - [email/activesync] Change jswbxml to run its unit tests under mocha. r=squib