Removed redundant event handler for Developer Materials.

This ensures that only one REST search is performed on loading the
page.

Also removed a usage that was present in a JavaScript inline.
DEVELOPER-244 Implement pagination for developer-material results.

The results are now paginated, and the pages are constructed only
when selecting a page to view. Also improves performances for
display of search results with a lot of hits.
DEVELOPER-349 Reset DM search results on clearing filter.
DEVELOPER-290 Fix to reset search results on 'Clear All Filters'.

This fixes the conflict among the event handlers triggered using
the same selector. The developer materials page also has a
'clear all filters' with the same class.

Also moved the event handling logic to the individual scripts.
Removed unnecessary logic to clear form.
Update jboss-developer.json

Remove `_readme` suffixes from `jbossdeveloper_quickstart` content type. It was used for:

- Elasticsearch index type (which means it did not match the mapping definition)
- `sys_type` (I removed it to make it consistent with other `sys_type`s defined in this file)
Update cdn.yml