Fix overlapping map markers

[cfrome77]

Breweries on the same street appear to be using the same coordinates. Find a way to make both markers appear on the map.

[cfrome77]

Lets see if either of these will work:

1. https://github.com/jawj/OverlappingMarkerSpiderfier-Leaflet
2. https://github.com/Leaflet/Leaflet.markercluster

[cfrome77]

I'll probably go with number 2 since it is provided by the leaflet.js team