Update the bundled Java Runtime Environment (JRE) on Windows to 8u31.

resources/install/installers.properties

@@ -13,7 +13,7 @@ windows.jre64.file=C:\\Install\\jre-7u17-windows-x64.exe
 
 # Paths to the ZIP files of private extracted Windows JRE setups to be deployed
 # as part of the respective setups of SIP Communicator.
-windows.jre.zip=C:\\Install\\jre-8u25-windows-i586.zip
-windows.jre64.zip=C:\\Install\\jre-8u25-windows-x64.zip
+windows.jre.zip=C:\\Install\\jre-8u31-windows-i586.zip
+windows.jre64.zip=C:\\Install\\jre-8u31-windows-x64.zip
 
 macosx.jre=${user.home}/bin/jdk1.8.0_25.jdk