* Read master key from environmental variable instead of from local file. This would allow us to pass it in via cfg2 ultimiately.
* Move the env var name to Constant.java
Benefits
1. Simpler setup - no need to download activator in order to build & run
2. Faster build - See https://engineering.linkedin.com/play/developing-play-applications-using-gradle
3. Streamlined dependency management - Everything defined in build.gradle, instead of build.gradle + build.sbt
4. Better integration with gradle lifecycle tasks - build, test, dist, clean all work as expected
Changes
1. Location of staging & distribution files moved from target to build
2. Use ./gradle -t runPlayBinary to run app with hot reload support
3. The generated start scripts are quite different from those generated by sbt
