Add map and direction to location show

add JS to location show erb
current user can see the direction to the other location on the show page.
try passing these into the function

Such as

```javascript
function calcRoute(originCoords, destCoords) {
  var origin = new google.maps.LatLng(originCoords[0], originCoords[1]);
  var destination = new google.maps.LatLng(destCoords[0], destCoords[1]);
  //....
}
```

```html
<script>
  calcRoute([<%= @location.latitude %>, <%= @location.longitude %>], [<%= current_user.location.latitude %>, <%= current_user.location.longitude %>])
</script>
```