Update release tag to vX.Y.Z (#1409)

java/pending_code_changes.txt

@@ -1,3 +1,6 @@
+GitHub project changes:
+ - Changed tag to vX.Y.Z from libphonenumber-X.Y.Z; this may affect ports and
+   derived projects.
 Code changes:
  - Using new possibleLengthInfo to decide whether a short number is the right
    length or not. This could result in more specific results; whereas before, a

java/pom.xml

@@ -146,7 +146,7 @@
         <artifactId>maven-release-plugin</artifactId>
         <version>2.2.1</version>
         <configuration>
-          <tagNameFormat>libphonenumber-@{project.version}</tagNameFormat>
+          <tagNameFormat>v@{project.version}</tagNameFormat>
         </configuration>
       </plugin>
       <plugin>