Gracefully handle network or configuration errors when accessing a switch.
Gracefully handle network or configuration errors when accessing a
switch.

- When attempting to contact a switch via eAPI, network/config
  issues cause an internal EapiException to be thrown.  This
  bubbles back up so that the top-level looping can skip that device
  and retry later.
- A portion of the same logic allows us to handle a temporary outage
  to a device, also.
- Fix a few pylint alignment warnings.

arista-eosext/rphm