RFR [9] 8157061: Add support for running jtreg tests from IntelliJ project

[Maurizio Cimadamore]

Hi,
this is a small follow up to the IntelliJ project support. This patch 
adds support for running jtreg tests.

Jtreg tests can be executed by clicking on the new run configuration 
(called 'Jtreg') in the top right corner. This run configuration will 
call jtreg on the currently selected test file. If an entire test folder 
is selected on the left pane, jtreg will execute all tests in that folder.

There is an additional ant property called 'jtreg.home'; this property 
is automatically initialized to point to the value of JT_HOME (in case 
the configure script has been run with --with-jtreg). If no JT_HOME is 
found, the value of this property is left empty - meaning that the user 
will be asked to fill in a value (which can be done by accessing the Ant 
Properties dialog in IntelliJ).

The proposed patch is available here:
[1] - http://cr.openjdk.java.net/~mcimadamore/8157061/

Cheers
Maurizio