Bug 27694: use HTML filtering on News Tool textarea

Bug 27694: use HTML filtering on News Tool textarea

To test:
1. Add some HTML enties to your codemirror in the News Tool. Example: <option value="(itype:DVD and loc:*NEW) AND NOT index-term-genre:&quot;television&quot;">Movies</option>
2. Save and re-eneter the tool, the HTML entites have been converted
3. Apply patch
4. Try again, HTML entities should not be converted

Signed-off-by: Ron Houk <rhouk@ottumwapubliclibrary.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>