Remove dart:http as a dependency

[evaisse]

Hello,

I need to update the dart:http package on my app, and I struggle to match the app_review http version dependency.

Don't you think it would be more reasonable to extract the http client from inside the app_review package and let user provide it on boot ? By giving an example in the documentation that would be a bit more tedious to implement but easier to maintain.

https://github.com/fluttercommunity/app_review/blob/master/lib/app_review.dart#L224

We could just add a Future Function() provider to the appreview constructor ?

And it's a breaking change for sure.

Thanks !

[victorandeloci]

i've removed the 1.1.0 version dependency in this fork: #90