cloud server for secure store

[wenjing]

For google cloud storage service, develop a tmcp server that a client can save its secure store data to the cloud and read it back,

This task may involve:

• research existing methods how this is done. current SDK uses askar api. research and compare other methods. choose a method to support.
• adopt or implement a server: if adopting, then port mcp to tmcp. otherwise implement from scratch.
• add functionality to resync with the cloud copy.
• write a document for this method: specification
• write a section to add to developer's getting started guide
• any support, test functions