Merge canonical/master
Stored function to get the subtree ids of an item
Checking for and enforcing no cycles in data model
* also contains a minor fix for showDisabled
* 409 CONFLICT returned if attempting to introduce cycle
Wanted to knock out any race conditions while I'm at it
Merge pull request #2 from jiwalker-usgs/master

Wanted to knock out any race conditions while I'm at it
Merge pull request #658 from jiwalker-usgs/noCycles

No cycles