Change icon for Android version

The icon is taken from Chrome Apps & Extensions Developer Tool
https://chrome.google.com/webstore/detail/chrome-apps-extensions-de/ohmmkhmmmpcnpikjeljgnaoabkaalbgc
Change icon for iOS version

The icon is taken from Chrome Apps & Extensions Developer Tool
https://chrome.google.com/webstore/detail/chrome-apps-extensions-de/ohmmkhmmmpcnpikjeljgnaoabkaalbgc

I made some minor effort to make the small size icons look ok, but they still
suffer from severe rescaling blur.