CLI: wait before trying to start the installation

[imobachgs]

Problem

The agama install command might find the Manager service busy even if the progress reporting has finished. It may start the installation process right before the service status has been updated (although it is effectively not busy).

• bsc#1210941

Solution

Let's try to make the agama install command more robust:

• Wait until the Manager reports to be idle.
• Retry (up to three times) if there is a problem.
• Stop reporting the progress while waiting. This command is expected to be used in the auto-installation scripts. We can add a monitor command for such a purpose.

Notes

• Error and progress reporting in the UI are far from ideal. But let's address that later.
• We could add switches to influence the number of retries and the time between them.

[coveralls]

coverage: 72.396% (-0.1%) from 72.505% when pulling 6d99825 on imobachgs:wait-before-install into f6152b0 on openSUSE:master.

[teclator]

LGTM