Integrate linter `ktlint` into `bin/lint.rb` and `bin/format.rb`

[mscottford]

See https://ktlint.github.io/ for documentation on installing and using ktlint.

• Add install instructions to README.md
• Add ktlint to bin/lint.rb
• Add ktlint to bin/format.rb
• Fix all issues that are identified by ktlint