closes #519 by adding an error when a duplicate time / frequency import is scheduled
Adds @ScanImporter and changes the ChannelImporterFactoryImpl to scan the classpath for this annotation. This should make the system much more extensible. We can also add more fields to the annotation to aid in version updates such as dates.
Merge pull request #527 from denimgroup/bugfix-tfgh519-validate-duplicate-scheduled-imports

closes #519 by adding an error when a duplicate time / frequency import ...
2.1final merge