v4.1.0

Thanks to @msomhorst for implementing the following:
- support for selecting by DataType in the SearchBuilder and ListBuilder
- update the XSD with latest openapi content

Besides that:
- the README has been updated to include a link to an example on
  how to configure JCenter as repository in a Maven project

API now usable for Java projects

So far the API was only used with Groovy projects
as Groovy marks protected classes public,
`SearchBuilder` and `ListBuilder` were perfectly fine
to use. But not in Java projects.
Now these classes have been made public, for use
with Java projects.

Add bintray publishing