Create medusa concept of Job (models in app/models/job).
The idea is that when we want to track the progress of a process
we'll create a job for it and that will facilitate such tracking.
Many of these classes will relate to Delayed::Job and hence will
be perform-able, but that needn't strictly be the case.

Made some things that we were doing with delayed job via .delay
go through a Job indirection so that they'l be trackable.
Add tracking of fits jobs and virus scan jobs in the dashboard.