Update to ehcache 2.10.6

Fixes gh-6411

gradle/javaprojects.gradle

@@ -15,7 +15,7 @@ ext.cglibVersion = '3.2.10'
 ext.commonsCodecVersion = '1.10'
 ext.commonsCollectionsVersion = '3.2.2'
 ext.commonsLoggingVersion = '1.2'
-ext.ehcacheVersion = '2.10.5'
+ext.ehcacheVersion = '2.10.6'
 ext.gebVersion = '0.10.0'
 ext.groovyVersion = '2.4.4'
 ext.hsqlVersion = '2.3.6'