Add tox target to detect schema changes

Fetches reference schema from public bucket
Still need define method for updating reference schema on merge.

tox.ini

@@ -6,6 +6,7 @@ envlist =
     api,
     ui,
     swagger,
+    validate-schema,
 
 [testenv]
 ;basepython = python2.7
@@ -71,3 +72,10 @@ deps =
 commands =
     make docker-compose-build
     make docker-compose-build-swagger
+
+[testenv:validate-schema]
+deps =
+    nodeenv
+commands =
+    make docker-compose-build
+    make docker-compose-validate-schema