Build failed on windows with lots of EOL violations

[YamStranger]

@dmarkov Looks like we need to add .gitattributes to force EOL of the repo.

[dmarkov]

@yegor256 please pay attention to this issue

[YamStranger]

@yegor256. It is known problem, qulice fail if default system EOF not like in linux. So we need add .attributes to repository for force setting Unix-like end of line to git repository.
AppVeyor use linux like EOF.
This repository will not build successfully if you install git, install maven, clone repo and just build.
Here is some examples of same problem at different repositories:
This is issue same as here jcabi/jcabi-maven-skin#24 (build failed on Windows)
same is here yegor256/takes#148
fix mast be like here https://github.com/jcabi/jcabi-aether/pull/59/files#diff-fc723d30b02a4cca7a534518111c1a66 or like here jcabi/jcabi-dynamo#43