Auth flow from Github auth

[nurmerey]

Update callback in git_auth file to do the following:

• [x] figure out how to get username from github auth & grab it
• [x] check if the user exists in DB
• [x] add token AND access_token to users DB & re-create user table
• [x] if user does not exist:
  • [x] do GET user and grab user information from Github API
  • [x] create a new user && create token for user
• [x] save the access_token
• [x] export git_auth and call it in server.js
• [x] make a post route within the github callback
  • [x] get access_token from callback
  • [x] get user's email
  • [x] check if they are in the database by searching email
  • [x] if user is not exist in the database, create a new user with new token and save to database
  • [x] if user exists, create new token

Potentially another PR:

• [ ] redirect to /token page with user token in the request