Search Multiple Words Causes Error "URI submitted has disallowed characters"

[MitchellMcKenna]

Cause:
Search uses urlencode() which turns spaces into plus signs (+) which is not a permitted character in the config.

Resolution:
Adding plus sign (+) to the permitted characters in application/config/config-sample.php

Note:
Any existing users will need to update their application/config/config.php manually, it should be
$config['permitted_uri_chars'] = 'a-z 0-9~%.:_\-+';