Set the LC release version to 0.4.0

Author: dmitry-timofeev

exonum-light-client/pom.xml

@@ -4,7 +4,7 @@
 
   <groupId>com.exonum.client</groupId>
   <artifactId>exonum-light-client</artifactId>
-  <version>0.4.0-SNAPSHOT</version>
+  <version>0.4.0</version>
   <packaging>jar</packaging>
 
   <name>Exonum Java Light Client</name>