move Listener to container on load for theme overrides and set priority.

This is required because Zikula_View_Theme is not initialized until after the Zikula_View renders the module templates. fixes #1783 

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #1783
| Refs tickets  | -
| License       | MIT
| Doc PR        | -