feat: refactor rest utils and add middleware

[swarley18]

• refactored the JSON write functions into a utils folder
• moved the Pins structs to a models folder
• added a middleware that does handles the verification of tokens and adds token to the context
  • now there is not a need to check the auth token at every endpoint

TODO: test locally. Everything should work. Write test for middleware, didn't since I'm not sure how the tests are to be written, this is a good framework for tests