Scala 2.12 support

[vigoo]

This PR adds Scala 2.12.1 to the supported compilers.
Had to remove some unused imports make it compile, no other change was necessary.

[mingchuno]

@vigoo
I have forked this repo and published it under new version.
https://github.com/mingchuno/aws-wrap

I have cross build scala 2.12.0 in my fork. You can use it directly. You can still submit a PR if you want the remove unused imports.

[vigoo]

@mingchuno yeah I already found it and started using it! Thanks!