Added EquipmentActions cross-ref

* Added EquipmentActions cross-ref table to Equipment schema, providing
the capability to have many equipment records associated with a single
Action.
* Deleted EquipmentID from Actions
* Added respective foreign keys
* Modified Equipment diagram to better illustrate changes
* Sorted field names in Actions to move Methods to 3rd field, right
below ActionTypeCV.  This is because a combination of ActionType and
Method define the action.