This commit removes a few long deprecated bits in the docs and in
code. It also updates the
release notes to include those removals, and highlights what has been
deprecated in 0.8. And it fixes a Sphinx warning when building the docs.
Replace session_strategy template tag with purchase_info_for_product in demo-site temaplates and doc. See https://github.com/tangentlabs/django-oscar/commit/a8a140fa94baa13f778f9a1529de8d5c2b75e3f2
Replace stockrecord_tags with purchase_info_tags in demo-site templates and docs as invented in oscar0.6. See https://github.com/tangentlabs/django-oscar/commit/6341b576bf9fa18c4dc1c78aaa88e174826763f6