Updated Schema to work with Delete Study and Delete Tree Functionality

Includes the changes to the schema to allow the ON DELETE CASCADE
features to work in the MySQL datastore, allowing the Study Delete and
Tree Delete features to work properly.
Delete Tree Confirmation Page Initial Commit

Adds a delete tree confirmation view, asking for final user
confirmation of removing a tree, while displaying the tree details.
Adds Delete Tree Function

Added a function to allow the clean / fast delete of a single tree from
a study. Also removes all corresponding snodes, and any otus only
referenced by the deleted tree. Done with a combination of backend
CASCADE and direct SQL injection to increase performance. See code
comments for more specifics.
Revert "Adds Delete Tree Function"

This reverts commit feb210d160881aed222a068bf5269f03311fb9d5.
Revert "Revert "Adds Delete Tree Function""

This reverts commit cb149ee015c79bc79f5b7d0e8332b9c483aee477.