Bump next version to 1.4.0

1.3.3 was released.
diff --git a/gradle.properties b/gradle.properties
index 72ac771..8f5cd99 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -16,7 +16,7 @@
 # under the License.
 
 group=org.apache.datafu
-version=1.3.3
+version=1.4.0
 gradleVersion=3.5.1
 org.gradle.jvmargs="-XX:MaxPermSize=512m"
 release=false
\ No newline at end of file