Localize notification_utils to the API

This changeset pulls in all of the notification_utils code directly into the API and removes it as an external dependency.  We are doing this to cut down on operational maintenance of the project and will begin removing parts of it no longer needed for the API.

Signed-off-by: Carlo Costino <carlo.costino@gsa.gov>

app/v2/errors.py

@@ -2,13 +2,13 @@ import json
 
 from flask import current_app, jsonify, request
 from jsonschema import ValidationError as JsonSchemaValidationError
-from notifications_utils.recipients import InvalidEmailError
 from sqlalchemy.exc import DataError
 from sqlalchemy.orm.exc import NoResultFound
 
 from app.authentication.auth import AuthError
 from app.enums import KeyType
 from app.errors import InvalidRequest
+from notifications_utils.recipients import InvalidEmailError
 
 
 class TooManyRequestsError(InvalidRequest):