(CPR-57) Style fixes

Now that the packaging repo has rubocop we need to have a baseline for
all future runs. This commit goes through and fixes all 316 detected
offenses.
Disagree. I find the uncommented slashes easier to follow. This could also be expressed as:

```ruby
exclude_path = %r{/ext/packaging|ext/osx/}

tar.templates ||= Dir[File.join(Pkg::Config.project_root, "ext", "**", "*.erb")].select { |i| i !~ exclude_path }
```

Rock/paper/scissor for `%r{}`?