Merge pull request #875 from senior/ticket/master/pdb-221

(PDB-221) Add facts to import/export
PDB-469 - Support Anonymizing Facts

This commit adds support for the anonymization of facts. The levels of
anonymization supported are:

 - none - no anonymization
 - low - only values with a fact name of secret, password etc
 - moderate - recognized "safe" facts are untouched, recognized
              facts with sensitive information (i.e. ipaddress)
              have their values anonymized
- full - all fact names and values are anonymized