Rules to add:
Bundler/OrderedGems: turn off, we always ignore this.
Layout/DotPosition: should be "leading", which is the default. However, we get comments like "Place the . on the previous line, together with the method call receiver" from Hound.
Layout/MultilineMethodCallIndentation: should be "indented".
Style/FrozenStringLiteralComment: turn this off.
Style/GlobalVars: allow "$elasticsearch" and "$rollout".
Style/SymbolArray: turn off, we always ignore this.
How to test: none, it's just Hound.