Controller: Extract more hardwired parameters to configuration

[ecklm]

• [x] Flowstat window size
• [x] OVSDB address
• [x] Base URL of the QoS app, now http://localhost:8080 (might be overkill, but it can happen that the QoS controller runs separately from the adaptive slicer)
• [ ] Eliminate static variables

[ecklm]

On class variables

The elimination of class variables is not necessarily reasonable at the moment. Making them instance-variables would not necessarily make a difference. Therefore to avoid these values baing moved back and forth between these scopes, they will be left still until the change actually becomes reasonable.

Reasons why they do not hurt

• AdaptingMonitor13 will only have one instance throughout the run of the controller (at least until I don't specify otherwise)
• QoSManager doesn't offer flexibility in regards to its class variables, so those values would be identical in every instance for now.
• Same with FlowStat
• ConfigHandler is specific to this use-case so the list of mandatory fields do not need to be customized.