reimplement server node refresh

adds a very basic disconnected page
do not redirect on XHR when all backend servers are unavailable, instead return 504

fixes #303
redirect to dashboard if no longer disconnected

fixes #332
change travis campfire settings
Merge branch 'play' of github.com:Graylog2/graylog2-web-interface into play
always set UTF-8 as body encoding

fixes #333
butt ugly change password form

needs design dude.
issue #330
stop some periodic polling when out of focus

fixes #328
Merge git://github.com/Graylog2/graylog2-web-interface into develop