RFR: JDK-8231277: Adjust Linux application image layout

[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).

This fix:

- directory layout of Linux app image adjusted to better comply with 
Linux FSH.
- some unused code clean up.
- added support to run JUnit4 tests along with the standard jtreg tests.
- DeployParamsTest.java jtreg test converted into JUnit test.
- unit tests added.

Baseline for the fix is 
http://cr.openjdk.java.net/~asemenyuk/8225249/webrev.02/ patch.

[1] https://bugs.openjdk.java.net/browse/JDK-8231277

[2] http://cr.openjdk.java.net/~asemenyuk/8231277/webrev.00/