This gist is a *VERY* simple server to spoof your location.

GeolocationSpoof.py

#
#   In about:config, edit the geo.wifi.uri to be http://localhost:8899
#   Restart Firefox
#   Profit!
#   Pretend you life somewhere in the Magic Kingdom
#

import json
import http.server
import socketserver


PORT = 8899
LAT, LNG = 28.373758, -81.549535

class GeoHandler(http.server.BaseHTTPRequestHandler):
    def do_GET(self):
        self.send_response(200)
        self.send_header("Content-type", "application/json")
        self.end_headers()
        self.wfile.write(bytes(json.dumps({
            "location": {
                "lat": LAT,
                "lng": LNG
            },
            "accuracy": 10
            }), "utf-8"))

    def do_POST(self):
        return self.do_GET()

with http.server.HTTPServer(("", PORT), GeoHandler) as httpd:
    print("serving at port", PORT)
    httpd.serve_forever()