[FEATURE] #110 Restructure dialog "Add XMPP/Jabber Account"

Not quite perfect but at least the create account button is shown in the
dialog layer and not in the page anymore.

Change-Id: I95a50ccad0d0c53e08c13d8edd23ce64b9ddf916
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1281
Reviewed-by: Franz Zieris <zieris@inf.fu-berlin.de>
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>