Fixes CDAP-1080 (Docker builds and starts CDAP, but HelloWorld doesn't run). This creates a property (router.address) that can be set on the Java command line inside a Docker container to the correct IP address, yet at the same time it doesn't interfere with a regular Standalone installation from successfully using localhost (127.0.0.1) as the IP to bind to.
Merge pull request #884 from caskdata/feature/r2.6.0_fix_docker

Fix Docker builds