Replace Bintray/JCenter

[keilw]

JFrog announced it will shut down Bintray and JCenter by the end of April: https://jfrog.com/blog/into-the-sunset-bintray-jcenter-gocenter-and-chartcenter/

This affects multiple aspects of the JavaMoney build process or download content:

• Maven - Fix Permissions for Sonatype Nexus: https://issues.sonatype.org
• Maven - Change additional repositories in every relevant POM. While "Artifactory installations with remote repositories configured against Bintray and Centers will not be affected by this sunset." is worth clarification, it does not sound like this applies to anything other than an Artifactory client but not e.g. a build job on a Circle-CI, the snapshot repositories like https://oss.jfrog.org/artifactory/oss-snapshot-local are most likely going away at least those few weeks after the sundown
• Maven - Deployment to Bintray Snapshot repositories won't work anymore. Trying that after May 1st will certainly break the build, so any use of CI_DEPLOY_USERNAME/PASSWORD or equivalent must point to something else, probably a Sonatype/Nexus user with appropriate permission to perform snapshot deployments