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

integration-tests/api/package.json

@@ -4,17 +4,19 @@
   "main": "index.js",
   "license": "MIT",
   "scripts": {
+    "test": "jest --runInBand",
     "build": "babel src -d dist --extensions \".ts,.js\""
   },
   "dependencies": {
-    "@medusajs/medusa": "^1.1.3",
-    "medusa-interfaces": "^1.1.0",
+    "@medusajs/medusa": "1.1.11-dev-1615544779907",
+    "medusa-interfaces": "1.1.1-dev-1615544779907",
     "typeorm": "^0.2.31"
   },
   "devDependencies": {
     "@babel/cli": "^7.12.10",
     "@babel/core": "^7.12.10",
     "@babel/node": "^7.12.10",
-    "babel-preset-medusa-package": "^1.1.0"
+    "babel-preset-medusa-package": "1.1.0-dev-1615544779907",
+    "jest": "^26.6.3"
   }
 }