Upgrade to Kotlin 1.1.51

Author: sbrannen

gradle.properties

@@ -14,7 +14,7 @@ apiGuardianVersion  = 1.0.0
 assertJVersion      = 3.8.0
 degraphVersion      = 0.1.4
 junit4Version       = 4.12
-kotlinVersion       = 1.1.4-2
+kotlinVersion       = 1.1.51
 log4jVersion        = 2.9.0
 mockitoVersion      = 2.9.0
 ota4jVersion        = 1.0.0