Provide easy way of logging output and metrics

[SamVanhoutte]

Provide an easy way of logging metrics and output:

When we are connected to AzureML workspace, link the output & metrics to a Run
When we are not connected, leverage the Python logging framework to output logging to the standard logging methods.

To be investigated: does the Python logging framework provide a centralized way to have one interface being used to log to multiple outputs (including AzureML)