separate definitions into separate files to allow reuse

see https://github.com/Julian/jsonschema/issues/98

took boring generic things (eg uuid) into definitions.json, and also
separated email and sms notification objects into respective files

tests/app/public_contracts/definitions.json

@@ -0,0 +1,12 @@
+{
+  "$schema": "http://json-schema.org/draft-04/schema#",
+  "description": "Common definitions - usage example: {'$ref': 'definitions.json#/uuid'} (swap quotes for double quotes)",
+  "uuid": {
+    "type": "string",
+    "pattern": "^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}$"
+  },
+  "datetime": {
+    "type": "string",
+    "format": "date-time"
+  },
+}