Updated the action buttons in the Extensions modulelist

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | -
| Refs tickets  | -
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Added color parameter and updated the .png images that did not work any more. It adds a little color to the module list and makes sure that module plugins have an icon again (like scribite for instance). I used paperclip for that.
Merge pull request #1071 from espaan/modlist_actionbuttons

Updated the action buttons in the Extensions modulelist