Add Buoy Discovery Support

[derekdowling]

Figure out how to find the nearest buoys programmatically for a given latitude/longitude.

[derekdowling]

Look at https://github.com/mpiannucci/surfnerd for inspiration.

[derekdowling]

Specifically: https://github.com/mpiannucci/surfnerd/blob/master/buoystations.go#L46.