Improve visibility of exceptions in asyncio routines, especially within 'run_in_executor'

The following code stalled at the await future line:

```
def _validate_thread(self):
proc = subprocess.run('echo hello', shell=True)
print("This causes an exception: ", proc.returncode())
return proc.returncode

async def validate(self):
"""Verify that the system is running and ready to commit an update"""
self._logger.info("Starting Validate")
future = SharedLoop.run_in_executor(self._validate_thread)

print("started process")
self._logger.info("Waiting for validation to complete")
rc = await future
```

This is because of the exception in the print statement.

The error is visible while the tasks are being cleaned up during a CTRL+C, but can become somewhat lost in output among all the other cleanup that occurs.

Reporting the exception in real time (perhaps with a certain amount of -v's) would be very helpful, as would be raising the visibility of the error print during cleanup. I'd suggest printing the stack or coloring the line red.