Merge pull request #63 from csmith/autovalue

Update to autovalue 1.6.

build.gradle

@@ -25,7 +25,8 @@ repositories.mavenCentral()
 
 dependencies {
     compile group: 'com.google.code.findbugs', name: 'jsr305', version: '3.0.1'
-    compile group: 'com.google.auto.value', name: 'auto-value', version: '1.3'
+    compile group: 'com.google.auto.value', name: 'auto-value', version: '1.6'
+    compile group: 'com.google.auto.value', name: 'auto-value-annotations', version: '1.6'
     compile group: 'com.google.guava', name:'guava', version: '19.0'
 
     testCompile group: 'junit', name: 'junit', version: '4.12'