RFR: JDK-8215381: Investigate if current implementation of --license-file is correct for Debian packages

[Alexey Semenyuk]

Please review the jpackage fix for bug [1] at [2].

This is a fix for the JDK-8200758-branch branch of the open sandbox 
repository (jpackage).

- change format of the default copyright file to comply with Debian 
packaging requirements;
- install copyright file in proper location to comply with Debian 
packaging requirements;
- introduce --linux-deb-copyright-file command line option to allow 
override of the default copyright file template

[1] https://bugs.openjdk.java.net/browse/JDK-8215381

[2] http://cr.openjdk.java.net/~asemenyuk/8215381/webrev.00/

Thanks,
Alexey