MinDevices, MaxDevices and Timeout should be available to every target manager

[mimir-d]

Issue by insomniacslk Tuesday Feb 04, 2020 at 16:35 GMT Originally opened as https://github.com/facebookincubator/contest/issues/15

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This is currently left to plugin implementations, which may or may not require their presence. We also need to reject jobs if no device is returned. The various Host and Device should become Target (i.e. MinTargets and MaxTargets) to have consistent naming.