Fix all tags being added to new Constraint/Scheduling Condition metadata

[duranb]

resolves #1522

To test:

1. Populate the tags table via plan creation, selected activity directive form, etc.
2. Go to /constraints
3. Click "new" to go to the constraint creation page
4. Don't add any tags to the metadata
5. Create the new constraint
6. Verify that no tags are present on the newly created constraint metadata
7. Navigate to the new constraint page again
8. This time add one or two tags
9. Create the constraint
10. Verify that only the tags you specified are added
11. Repeat steps 3-10 but for scheduling conditions instead (should be a fairly identical process)