Show avatar also by EXTVAL (url), not only by BINVAL

Many sites have already the user avatar url, and in such case it’s good
to use just url, not to generate and store another blob.
Little fix
Merge pull request #100 from Zalmoxisus/master

Show avatar also by EXTVAL (url), not only by BINVAL
Fix offline subscription request (fix #102)
fix disco response with unknown node name for caps
Adapt css for multichat
Login without window reload (as in Diaspora)

jsxc.xmpp.login() -> jsxc.login();
Patch from https://github.com/diaspora/jsxc/pull/5
Restore old connection only after login is done and connection is ready
Prevent duplicate connections
Fixes showing presence
Disable OTR
Remove settings menu
Remove showContactDialog function

Use jsxc.xmpp.addBuddy(username, alias); instead of
jsxc.gui.showContactDialog();
Add subscription roster group 'chat'
auto backsubscribe
Remove dialog when accept subscription request (just send subscribe stanza back)
Remove detectEmail and XEP-0147 url

https://github.com/sualko/jsxc/commit/7ea444276bedf4c29b81b7081a426d9e08
b5c6fc
https://github.com/sualko/jsxc/commit/91def2febcf621dd72df50849e564bdc7c
07bedb
https://github.com/sualko/jsxc/commit/d102d41f6b500f14c2c97abf692abef8a4
879ce5