Allow ecm_prep.py to continue past ECMs that trigger exceptions

[trynthink]

When an ECM is encountered that is nonconformant for some reason, rather than raising an exception and exiting, change the behavior of ecm_prep.py to skip past that ECM and continue preparing the remaining ECMs.

[trynthink]

Create some kind of log file with which ECMs failed and the exceptions that were triggered. Add check in run.py to warn the user again if ecm_prep.py failed to successfully handle an ECM.