Because of my production environment, adding a JSON file a little bit of
a pain. However: using the intializer it's readily possible to set my
credentials manually from my environment. I noticed that while all the
credential details can be either a String or a Symbol, the 'flow' (i.e.,
`web`) **must** be a string.
This allows it to accept both a string and a symbol.
JSON has been part of the ruby stdlib since 1.9.0 (see
https://github.com/ruby/ruby/commit/af1c4167), and the latest version of
google-api-client requires ruby 2.0 or better so we can assume it's available