Upgrade Mockito version to 2.9.0

Author: sormuras

gradle.properties

@@ -16,7 +16,7 @@ degraphVersion      = 0.1.4
 junit4Version       = 4.12
 kotlinVersion       = 1.1.4-2
 log4jVersion        = 2.9.0
-mockitoVersion      = 2.8.47
+mockitoVersion      = 2.9.0
 ota4jVersion        = 1.0.0
 shadowVersion       = 2.0.1