Handle manager/group commits without a instance plugin

[kaufers]

Flow:

• Start instance, manager, group plugins
• Issue manager group commit

If the instance plugin is not yet available (some startup processing has not yet completed) then the manager commit fail (because it cannot find the instance plugin).

Can this be updated to:

• Commit command is accepted
• manager/group plugin continues the commit attempt in the backgroud

This basically makes the commit asynchronous; it will eventually work once the instance plugin is available.