Feature/backend auth forgot password

[montekaka]

Adds forgot password, it will also allow pre-existing volunteers to sign up to our service.

Forgot password implemented as

1. User makes a POST request to /auth/forgot_password with its 911 VM email address.
2. Then we will find the user from database with the email address, and generate an access token and expires date (e.g. now + 30 mins)
3. Send an reset password email with the access token
4. Allow user to create a new password with the access token