JBIDE-17182 org.jboss.tools.jsf.test tests failure on Windows

"Div by Zero" exceptions are fixed in XHTMLValidatorTest.

Signed-off-by: Victor V. Rubezhny <vrubezhny@exadel.com>
JBIDE-17184 org.jboss.tools.jsf.ui.test failure on Windows
JBIDE-15937 All seam runtimes are checked after adding/removing

Added validation instead