Changed maxOccurs on Observable_Source field in ObservableType from 1 to unbounded
Added sighting_count attribute to the MeasureSourceType for capturing the number of times the observation source has seen a given Observable
Added sighting_count attribute to the ObservableType for capturing the number of times it has been seen
Merge remote-tracking branch 'upstream/version_2.1' into issue_79
Merge remote-tracking branch 'upstream/version_2.1' into issue_79
Merge pull request #278 from ikiril01/issue_79

Added Support for Capturing Observable Sightings