Improvements to EDS upload rake task

• Add datestamps to logfile entries
• Be sure the word "Error" appears in error notifications to Slack. For instance, the message, didn't:
  • Unable to upload file for crdl portal full update. Unable to negotiate with 140.234.252.111 port 22: no matching key exchange method found. Their offer: diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1