[WIP] Admin module jQuery migration

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | yes
| Deprecations? | yes
| Tests pass?   | na
| Fixed tickets | 
| License       | MIT
| Doc PR        |

For now there's not so much about Admin module migration - work is still in progress.
Few new things:

  - [ ] first two UI widgets - zAccordion and zPanels
  - [ ] zikula's context menu plugin (customisation of jQuery Medialize Context Menu)
  - [ ] zikula's js templates (customisation of underscore template engine and draft for remote templates)