Theme fixes

This PR fixes a few issues in the theme module and related code

1) Fixed the display of the "all items" element of the abcpager plugin
2) Added the all items element to the theme module filter
3) Fixed the filtering of theme to the display name. I believe this has been addressed in another PR so this is a duplicate fix.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | 
| Refs tickets  |
| License       | MIT
| Doc PR        | 

-Mark