Initialise gems

 - Windows support (tzinfo-data)
 - PostgreSQL gem/schema gems
 - various development helper gems
 - Puma as the App Server
 - HAML as the templating engine
 - YARD for documentation
 - RSpec for testing
 - Simplecov for code coverage
 - Factory Girl for factories over fixtures.
Prefer single-quoted strings when you don't need string interpolation or special symbols.