To support new APIs in version 2.1.1

[PrathibaJee]

Following APIs shall be supported as per the specification ,

• /v1/dispose-remainders-of-deregistered-application
• /v1/inform-about-preceding-release
• /v1/update-client-of-subsequent-release

[PrathibaJee]

Issue merged to branch v2.1.1_impl as a part of the PR #967.
Hence closing this issue.