Feature iterator/generator

[gzt5142]

The CrawlerSource object holds information and methods about sources.
Right now, we have a separate function which takes that source to generate a collection of features (via ijson and a download function). Because that code will never be used without access to a specific feature, I believe it would be better to turn it into a method on the CrawlerSource object.

sources = src.SQLRepo(db_uri)   # ...or CSVRepo() ...or JSONrepo()
source = sources.get(source_id=13)
for f in source.get_features():
   # yada, yada, yada

[gzt5142]

The main question here is whether to download the entire JSON data from the source, then parse the local file, or whether it is safe to create Feature instances from the network stream directly.

[dblodgett-usgs]

As long as it is happening in a temp table, streaming would be preferable?