Updated cron plugin manifest

Updated author, creation date, email, and URL to match component
manifest, and incremented version number
Fixed message type on category sync error
Added missing SQL update files

Joomla requires these files (even if empty) to cascade update properly.
Fixes missing Published State row from 0.6.
v0.6.1 - Published Date added to Import Order

Article dates can now be set as the published date (when article is
approved).