#2668 - Initial changes for default price ID
#2668 - Adding Unit Tests for new function
#2668 - Removing ksort to choose first item, not lowest index
#2668 - Adding 'since' to docblock based off Milestone.
#2668 - Setting first item as default when variable is selected.
Merge pull request #2709 from easydigitaldownloads/issue/2668

Add ability to set default price ID