Add View_Helper to handling dialogs (jQueryUI)

- extend destroy method of views which uses dialogs to destroy these
Add tests for DSD and DS; Move View_Helper to CubeViz_View_Helper

- a lot of refactoring
Complete test for DSD (questionMark dialog)
Rename onChange_selectedDSD to onAfterChange_selectedDSD

- use onBefore*_* events one the beginning of a function, and
onAfter*_* at the end > to have more control about events
Add test for open questionMark dialog in dataSet
Add tests for Component View; rename cubeviz-component-questionMarkDialog to cubeviz-component-dialog
Add tests for CubeViz_View_Helper.ts
Add test to check if select component elements dialog was created as expected

- check elements in the ul element by element