[feature] Add API endpoint that returns co-ordinates on indoor map (floorplan)

[pandafy]

Add an API endpoint that takes the location ID and returns co-ordinates of all the devices.

• It should also return all available floors in the location.
• It should be possible to filter the devices based on the floor.

[dee077]

Appraoch

• The current implementation of the draft PR returns data in JSON format; this should be updated to return GeoJSON format to be compatible with netjsongraph.js for rendering the floorplan map.
• Filter class is already been made.