Background jobs service

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Feature Request

Is your feature request related to a problem? Please describe

Performance and continued development are hampered by having to complete all things synchronously.

Describe the solution you'd like

Add a always running container that can do more long running data operations when asked to via some interface. For example the git fetching of dab repo list could be done periodically and asynchronously to make the command much faster as that operation was done in the background recently.

Describe alternatives you've considered

Doing things synchronously can make every command slow even when they should be quick. Have also made some hooks run in the background however because the final action must be to wait for them to finish the gains are small.

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Could also handle image updates for dab apps.

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Might be able to use some existing generic message/job queue service.

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Things to run periodically in the background:

• fetch on all repos to make report list near instant
• update the dab image so normal operations are not slowed unexpectedly
  Events to handle in the background:
• dab commands logged and annotated in chronograf