Introduces flow types for storage (#4349)

* Introduces flow types for storage

* Better typing of QueryOptions

* Adds flow types to SchemaCOntroller,

- runs flow on pre tests
- fixes flow

* Adds ClassLevelPermissions type

* Moves Controller types into a single file

* Changes import styles

* Changes import styles

* fixing method setIndexesWithSchemaFormat (#4454)

Fixing invalid database code in method `setIndexesWithSchemaFormat`:

* It must be a transaction, not a task, as it executes multiple database changes
* It should contain the initial queries inside the transaction, providing the context, not outside it;
* Replaced the code with the ES6 Generator notation
* Removing the use of batch, as the value of the result promise is irrelevant, only success/failure that matters

* nits

* Fixes tests, improves flow typing

package.json

@@ -56,6 +56,7 @@
     "deep-diff": "0.3.8",
     "eslint": "^4.9.0",
     "eslint-plugin-flowtype": "^2.39.1",
+    "flow-bin": "^0.59.0",
     "gaze": "1.1.2",
     "jasmine": "2.8.0",
     "jasmine-spec-reporter": "^4.1.0",
@@ -66,7 +67,7 @@
   },
   "scripts": {
     "dev": "npm run build && node bin/dev",
-    "lint": "eslint --cache ./",
+    "lint": "flow && eslint --cache ./",
     "build": "babel src/ -d lib/ --copy-files",
     "pretest": "npm run lint",
     "test": "cross-env MONGODB_VERSION=${MONGODB_VERSION:=3.2.6} MONGODB_STORAGE_ENGINE=mmapv1 TESTING=1 jasmine",