[ASENG-868] Implement StopOnError config for graph building

[edznux-dd]

This PR propose a fix for #144 by adding a config to allow continuing building the graph even after there are some errors. The default config is to continue on error, but print error message.

The long term solution will be to add an error handling module that tracks and display the error, criticality and source of the issues in a human readable way.

The error message should be very explicit that it may create an incomplete graph and thus cause inaccurate (false negative) results.

[edznux-dd]

Looks like this correctly solved the issue we encountered without unintended side effects, merging.