chore: Pass bintray credentials as env variables
chore: Pass bintray credentials as env variables

It looks that System.getenv('BINTRAY_USER') of our publishing.gradle is
not working in circleci environment (maybe because is a docker container
with different env?). Now we are passing directly to gradle publish
those credentials already stored in circle-ci.

swisscom/open-service-broker,swisscom/open-service-broker