chore: improve JSDoc ESLint rules (#1147)

- Prefer `@returns` to `@return`
- Prefer `@param` to `@arg`
- Prefer capitalised types

See: https://github.com/resin-io/etcher/pull/1111#discussion_r103483879
Signed-off-by: Juan Cruz Viotti <jviotti@openmailbox.org>

.eslintrc.yml

@@ -71,6 +71,17 @@ rules:
     - error
     - requireReturn: false
       requireReturnDescription: false
+      requireReturnType: true
+      requireParamDescription: true
+      preferType:
+        boolean: "Boolean"
+        number: "Number"
+        object: "Object"
+        string: "String"
+        array: "Array"
+      prefer:
+        arg: "param"
+        return: "returns"
   valid-typeof:
     - error
 

lib/gui/models/selection-state.js

@@ -105,7 +105,7 @@ SelectionStateModel.service('SelectionStateModel', function(DrivesModel) {
    * @function
    * @public
    *
-   * @returns {object}
+   * @returns {Object} image
    *
    * @example
    * const image = SelectionStateModel.getImage();