Wire up error handlers.

Replace some 400s with more appropriate 500s.

DAO methods that cause unexpected exceptions get caught and
logged by errors.py 500 error handler.

app/template/rest.py

@@ -1,5 +1,8 @@
-from flask import Blueprint
-from flask import (jsonify)
+from flask import (
+    Blueprint,
+    jsonify
+)
+
 from sqlalchemy.exc import DataError
 from sqlalchemy.orm.exc import NoResultFound
 
@@ -8,6 +11,9 @@ from app.schemas import (template_schema, templates_schema)
 
 template = Blueprint('template', __name__)
 
+from app.errors import register_errors
+register_errors(template)
+
 
 # I am going to keep these for admin like operations
 # Permissions should restrict who can access this endpoint