Make the /harvest page more robust if source.status is not set

This prevents exceptions from appearing in the log from Jinja:
  [error] [client 1.2.3.4] Error - <class 'jinja2.exceptions.UndefinedError'>: 'dict object' has no attribute 'status'
Hide both the label and the number of datasets when 'status' is not available
[#59] Ignore auth in the CKAN harvester
[#36] Fix bug on API version checking
[#61] Ignore harvest sources on the CKAN harvester