Prepare release 1.2.0

Change-Id: I56f29b049237474df17bb69f29855ffcbbe90554
diff --git a/build.gradle b/build.gradle
index 9761d95..48d82bf 100644
--- a/build.gradle
+++ b/build.gradle
@@ -16,7 +16,7 @@
 }
 
 group = 'net.named-data.jndn-extra'
-version = '1.1.1'
+version = '1.2.0'
 
 sourceCompatibility = JavaVersion.VERSION_1_8
 targetCompatibility = JavaVersion.VERSION_1_8