removed excessive escaping

No need to escape room-jid, while leaving, as Strophe.muc.leave() does escaping on its own

see: https://github.com/strophe/strophejs-plugins/blob/5e65dda2f0b406f91afcd4ed2a9124e9a7ad626e/muc/strophe.muc.js#L143 and https://github.com/strophe/strophejs-plugins/blob/5e65dda2f0b406f91afcd4ed2a9124e9a7ad626e/muc/strophe.muc.js#L580
Merge pull request #277 from indeyets/patch-1

removed excessive escaping
Log strophe messages to console when debug mode is on

Log errors at appropriate level. This mostly addresses https://github.com/candy-chat/candy/issues/248#issuecomment-50351725, with the exception that the original exception's stack trace is lost. This is [Strophe's fault](https://github.com/strophe/strophejs/blob/master/src/core.js#L2219-L2222) and we can't fix it ourselves.