Add version info to site (Git SHA footer)

[evanwill]

• [x] Set up dotenv and ensure you have an environment variable the references the name of your project.
• [x] edit config/initializers/git_sha.rb
• [x] edit app/views/shared/_footer.html.erb

Helps with having info visible for debug / reporting issues, https://curationexperts.github.io/playbook/every_project/git_sha.html

[evanwill]

looking at implementation in https://github.com/curationexperts/mahonia

[evanwill]

using dotenv-rails, https://github.com/bkeepers/dotenv

[evanwill]

learned that the example is based on DCC specific deploy environment, not sure if this is going to work well...

[evanwill]

closed with PR #12