Adding support for geocoding of a Boston Public Library Flickr Album

All of the work was done in my second commit of this request.  It's description is pasted below.  I was able to geocode 207 of the 615 photos which is 33.66%.  Using hamstermap.com/quickmap.php to visualize the output, we have pretty dense coverage of Charlestown, MA
![screen shot 2014-04-13 at 8 27 06 pm](https://cloud.githubusercontent.com/assets/2768090/2690930/a1a81366-c36b-11e3-99f5-b1e8b5fbfb4c.png) 


1) Adding code to scrape photos and their information from flickr and
pickle it in the correct record format
— Currently targeted for the Charlestown Lanterns album from the BPL
but can easily be extended
Album is
https://www.flickr.com/photos/boston_public_library/sets/721576224739024
47/
2) Adding MA specific resources to aid in geocoding
3) Adding a coder to geocode street text from the photos from
Charlestown Lanterns
4) Adding a coder to geocode certain points of interest from
Charlestown Lanterns
5) Added some backwards compatibility for the generate-geocodes file
—This is no longer used in my commit, but it doesn’t hurt to have it in
case people want to use the sf geocodes
6) Adding support for the —output_format = failed_geocode.txt' which
outputs photos that could not be geocoded
7) Added a method to calculate the lat lon in the middle of two
intersections