[#1155] Document how to upgrade the dependencies
[#1155] Tweak upgrading dependencies docs
Merge branch 'master' of github.com:okfn/ckan into 1155-document-upgrading-dependencies
[#1155] Explain how to pin the latest uncompatible version in requirements.in
[#1155] Add a small clarification to the docs
Merge branch '1155-document-upgrading-dependencies'