Improved output for test-status target

[Vincent4486]

Added a condition in the target test-status in build.xml to print "None" when there are no tests skipped or failed. This patch uses a new approach to displaying the list of skipped/failed tests by adding a condition before the print to make the string display "None" when it is empty.

Bug 69890

Before:

test-status:
   [concat] Testsuites with skipped tests: 
   [concat] Testsuites with failed tests: 

After:

test-status:
   [concat] Testsuites with skipped tests: 
   [concat] None
   [concat] Testsuites with failed tests: 
   [concat] None