Working on Save node selections in browser storage #117

- node selections in the "MakeReservationDialog" can now be saved on loaded using the local storage
- functionality is implemented in two button classes

Still to do:

- allow saving/loading multiple different configurations named by the user
- allow saving/loading reservation-specific configurations
- embed functionality in different contexts (e.g., flash/reset/... controls), e.g. by embedding it into the wisegui-node-table.js instead of the reservation dialog