TEIIDDES-1838, 1839, 1834

- TEIIDDES-1839 Fixed 'Add' button enablement in Reconciler Panel
- TEIIDDES-1838 Fixed Constants display issue in Reconciler Panel
- TEIIDDES-1834 Added preference for generation of QueryPlans upon execution and added controls to the Teiid Execution Plan View.  Defaults to 'true' but the user can set 'false' if desired.