Update to Jackson 2.9.1

Issue: gh-4608

gradle/dependency-management.gradle

@@ -39,9 +39,9 @@ dependencyManagement {
 		dependency 'ch.qos.logback:logback-classic:1.2.3'
 		dependency 'ch.qos.logback:logback-core:1.2.3'
 		dependency 'com.codeborne:phantomjsdriver:1.4.0'
-		dependency 'com.fasterxml.jackson.core:jackson-annotations:2.9.0.pr4'
-		dependency 'com.fasterxml.jackson.core:jackson-core:2.9.0.pr4'
-		dependency 'com.fasterxml.jackson.core:jackson-databind:2.9.0.pr4'
+		dependency 'com.fasterxml.jackson.core:jackson-annotations:2.9.1'
+		dependency 'com.fasterxml.jackson.core:jackson-core:2.9.1'
+		dependency 'com.fasterxml.jackson.core:jackson-databind:2.9.1'
 		dependency 'com.fasterxml:classmate:1.3.3'
 		dependency 'com.github.stephenc.jcip:jcip-annotations:1.0-1'
 		dependency 'com.google.appengine:appengine-api-1.0-sdk:1.9.23'