Added tests for bad metadata.

Shows KSP-CKAN/CKAN-meta#182 .
Better handling (ignoring) of bad upstream metadata.

Closes KSP-CKAN/CKAN-meta#182.
GUI: Change the forum link in the "about" to the new thread.

It was previously pointing to the old one.
Merge pull request #686 from pjf/fix_about

GUI: Change the forum link in the "about" to the new thread.
Merge pull request #685 from pjf/handle_bad_metadata

Ignore rather than die on bad metadata.