Update VTN Coordinator README for Helium release.

  * Tomcat server instance is installed by VTN Coordinator, and
    it is started by vtn_start.
  * Tomcat server port was changed to 8083/tcp.
  * Version number in README is controlled by pom.xml.
  * VTN Coordinator API version was changed to V1.1.

Change-Id: Id5e28158cfc164e337a0445632148014f6b8a649
Signed-off-by: Shigeru Yasuda <s-yasuda@da.jp.nec.com>
Merge "Update VTN Coordinator README for Helium release."