Fix license checks in headers for sbt buid

## Background
Currently, Cobrix copyright headers contain year ranges, e.g. `2018-2019`.
According to @GeorgiChochov,
> `sbt headerCheck` doesn't work with `2018-2019` in the license header, expected only `2018` and I can't override it for some reason

## Feature
When `sbt-header` plugin allows a workaround for ranged years in copyright headers, add a chacking task to the `sbt` build.