User signin

[mazma1]

This will provide an endpoint for only registered users to log in to their accounts. Users should be able to log in with with their usernames/emails and passwords.

This endpoint is expected to return an authentication token (JWT) with only the username encoded.

Endpoint:
POST /auth/signin

Response spec:

{ ​ 
    "token":​ ​"45erkjherht45495783" //JWT signed with only the username
}

Edge cases to keep in mind:

• Only valid inputs should saved to the database. Validate/sanitize all user inputs
• Responses should be sent with the appropriate status codes
• Handle errors properly and return appropriate error messages like so:

  { ​ 
     "error":​ ​"appropriate error message"
  }
  

[asi309]

Is this issue open? If yes I can contribute