Amphora authentication - Githubissues

Moves all user handling logic from amphora into amphora-authentication project
Removes test cases concerning user authentication
Refactors routes file
Code clean up

Do npm install to get amphora-authentication package
Run npm run test to verify that all tests are passing and code coverage is at 100%
Link the amphora module to a clay instance
Add the local provider to the array of supported providers when setting up amphora
Import a new user into your clay instance that supports local auth:
```
-
username: murena
password: secret
provider: local
auth: admin
```
Check that the user is able to login with username and password as well as with any other provider
Verify that the /_users routes are working as expected (they shouldn't show the user password)

clay / amphora