Added swift formatter, skipping unused check, and commit hooks

[Panajev]

Finding this tool useful @s4cha and wanted to contribute a bit since I am using it in projects now :).

I have added a swiftlint configuration file, a script that runs swiftlint in autocorrect mode as well as swiftformat (configured to complement and not work against swiftlint... added a Dangerfile too for Danger integration that could be used with Travis/CircleCI/etc....). Pretty much what I do on other projects, hopefully it is useful.

Formatting Rules
Link to rules for swiftformat and swiftlint (rules opted in and opted out can be seen in the script and in the swiftlint .yml configuration file):

• https://github.com/nicklockwood/SwiftFormat/blob/master/README.md
• https://github.com/realm/SwiftLint/blob/master/Rules.md

Danger integration notes (optional)

• The way I normally integrate danger is the ruby based version of the tool: https://danger.systems/ruby/
• This Dangerfile requires base danger, but also the following
  • danger-swiftlint: https://github.com/ashfurrow/danger-ruby-swiftlint
  • danger-swiftformat: https://github.com/garriguv/danger-ruby-swiftformat

[Panajev]

Any update?