Update to powermock:1.6.5

Fixes gh-5821

gradle/javaprojects.gradle

@@ -27,7 +27,7 @@ ext.jettyVersion = '6.1.26'
 ext.jstlVersion = '1.2.2'
 ext.junitVersion = '4.12'
 ext.logbackVersion = '1.1.11'
-ext.powerMockVersion = '1.6.2'
+ext.powerMockVersion = '1.6.5'
 ext.seleniumVersion = '2.44.0'
 ext.servletApiVersion = '3.1.0'
 ext.slf4jVersion = '1.7.25'