loading message counts now non-static

moved to MessagesService and removed unused classes
use instance to call .get
remove obsolete try-catch block
methods to change Input move to Node

Input is mostly a data access object now, Node has most of the responsibility to create/terminate inputs (as they are owned by inputs anyway)
use correct Node constructor during startup
use search factory for universal search creation

makes it possibly to transparently inject stuff :)
remove unused class
use field instead of class to access ApiClient
Merge git://github.com/Graylog2/graylog2-web-interface into develop