fix(examples): update examples to use geofire 5.x.x and firebase 5.x.x, fixes #182

[MichaelSolati]

Description

Update the example applications to use Firebase 5.x.x and GeoFire 5.x.x

Code sample

In the head of the HTML files:

<!-- Firebase -->
<script src="https://www.gstatic.com/firebasejs/5.9.4/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/5.9.4/firebase-database.js"></script>

<!-- GeoFire -->
<script src="https://cdn.firebase.com/libs/geofire/5.0.1/geofire.min.js"></script>

And when we create a GeoFire instance in the JavaScript:

// Create a new GeoFire instance at the random Firebase location
var geoFireInstance = new geofire.GeoFire(firebaseRef);

[coveralls]

Coverage decreased (-3.2%) to 91.346% when pulling cc0e4b7 on MichaelSolati:fix/examples into cdc7cac on firebase:master.