XMPP diaspora chat feature

Vines is located here diaspora/vines
Jsxc is located here diaspora/jsxc

* Implemented reset_authentication_token
* In respect of an unclean logout process we reset the token on sign in and sign out
* Added database tables for xmpp server
* To fully support external clients it should be also possible to save non-diaspora contacts
* Disable chat on default
* Enabled cross-domain messages
* Moving all vines config parameters to diaspora.yml
* Add switch to enabled self-signed acceptance
* Added blacklist host option
* Add xmpp service to foreman file
* Added chat option to aspects
* Add chat option to diaspora front-end
* Replacing jappix with jsxc client
* Updated jsxc initialization and enabled debug logging on default
* Use diaspora logout element for jsxc
* Added offline message table for XEP-0160
* Add max_offline_msgs option to config
* Set positive presence priority for jsxc on default
* Added jasmine test for toggleChatPrivilege
* Added spec for jsxc helper
* Disabled temp. OTR support