Added ability to sign in via username; separated email sign in and sign up config settings

docker/dev/config_docker.json

@@ -66,6 +66,8 @@
     },
     "EmailSettings": {
         "EnableSignUpWithEmail": true,
+        "EnableSignInWithEmail": true,
+        "EnableSignInWithUsername": false,
         "SendEmailNotifications": false,
         "RequireEmailVerification": false,
         "FeedbackName": "",