Fix deletion of management server floating IP in cleanup script

Created by: matofeder

The cleanup script's function resourcelist wrongly filtered the floating IP of the management server. The function returned brackets ]} on the end of the floating IP string which caused an issue.

This PR extends resourcelist function arguments with an argument that allows a custom definition of sed expression which filters the output of the function. The custom sed expression is then used to filter the management server floating IP without unwanted brackets on the end.

Closes #342 (closed)