Run automatic rubocop corrections

[billdueber]

Adds a .rubocop.yml and runs the autocorrect (rubocop -E)

Most the changes are minor formatting (spaces in some places,
indentation in others) and making sure the frozen string
literals are in every file.

Intellij products should pick up the .rubocop.yml file
and use it to provide inline hints when editing a file.

I don't particularly care about most of this stuff,
but we can run it for every PR and then at least
have some consistency.

[billdueber]

Diverged too far from master. Will try again later.