Remove unused api method
Get the plot id from the right place
Photos are at the root of the context dictionary

In OTM1 these were found directly on a given tree. With OTM2 these are,
instead, part of the outer dictionary.
Use the URL provided by the API

The API provides *either* an absolute url or a url relative to the root
of the site.
Merge pull request #63 from azavea/topic/photos

Topic/photos