Remove callback usage from console.py

In command.py, settled on coroutine structure as the sole design
pattern to support.  To be consistent, abolish the use of callback
from console.py as well so that SOL does not needlessly act so different
from command.py in the scenarios where it can act the same.

Change-Id: I7a26a7c9b929ef7e63ca23c595a28baeb7f1e1b9
Merge "Remove callback usage from console.py"