Sync plugin's getLatestModifiedTime should return the latest system time if no updates exist

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 6.2.0 CE RC2
• Fix Version/s: 6.2.0 CE RC2, 6.2.X EE
• Component/s: Documents & Media, Sync Connector
• Labels: None
• Branch Version/s:
  6.2.x
• Backported to Branch:
  Committed
• Git Pull Request: https://github.com/mikemanyoung/liferay-plugins/pull/76

Sync plugin's method getLatestModifiedTime() is used to return the latest time since the last modified document on the portal to make sure we only request documents after that time. If there are no documents on the portal, then the latest time should be the current system time on the portal since no documents exist prior to the current time.