feat(medusa): cart context (#201)

- Adds a context field to Cart
- context is automatically populated with ip + user agent
- context can be updated via POST /store/cart/:id or set when creating via POST /store/cart

scripts/integration-tests.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+medusa-dev --set-path-to-repo .
+
+cd integration-tests/api
+
+medusa-dev --force-install --scan-once
+yarn test
+
+