Update ballerina-parent version

ballerina-bot · ballerina-bot · commit 12d31a1348f8 · 2017-06-12T10:09:36.000+05:30
diff --git a/pom.xml b/pom.xml
@@ -21,7 +21,7 @@
     <parent>
         <groupId>org.ballerinalang</groupId>
         <artifactId>ballerinalang</artifactId>
-        <version>0.88-SNAPSHOT</version>
+        <version>0.88</version>
     </parent>
 
     <modelVersion>4.0.0</modelVersion>
