Common code for spendright-scrapers

This is a small library containing common code for the various spendright scrapers.

For now, the best approach is to include this as a submodule, and link to the srs package:

# From the top level of your git repo:
mkdir submodules
git submodule add git@github.com:spendright-scrapers/srs.git submodules/srs
ln -s submodules/srs/srs