As discussed, this refactor should satisfy all the criteria of
what the package should be doing.

To tell the usecase to be more clearer and I fix some typo in it.

Because calling a network image is not a reliable solution. So
instead of using Image.network, I switch to Image.asset for
displaying the Google Play Logo.

To make the user trying this package with ease.
Also having an example can add 10 points on pub.dev score.

This reverts commit 6c36438.