Add an indexedDB file storage example: image-reference-collector (#224)

* new example: image-reference-collector (indexedDB file storage demo)

* fix: added missing deps, updated all npm dependencies and webpack config to v.2

* chore: Renamed the example to store-collected-images

* chore: Removed from utils/image-store any direct call to the UI code

* move example built using webpack into its own subdir

* tweak browser action title

* added plain webextension example (without webpack build step)

* added README.md file to plain webextension example

* small changed based on the review comments

* fixed typo in store-collected-images example (webpack-based version)

* Remove React from the store-collected-images (plain webextension version)

* Fix eslint errors on store-collected-images example (both versions)

* Fix some typos in the README files

store-collected-images/webextension-with-webpack/extension/manifest.json

@@ -0,0 +1,26 @@
+{
+  "manifest_version": 2,
+  "name": "store-collected-images",
+  "version": "1.0",
+
+  "icons": {
+    "16": "images/icon16.png",
+    "48": "images/icon.png"
+  },
+
+  "browser_action": {
+    "default_icon": {
+      "48": "images/icon.png"
+    },
+    "default_title": "Collected Images"
+  },
+
+  "background": {
+    "scripts": ["dist/background.js"]
+  },
+
+  "permissions": [
+    "contextMenus",
+    "<all_urls>"
+  ]
+}