Allow action.auto_create_index to be set with a comma delimited white or black list of index patterns that are allowed or disallowed to be automatically created.

For example, setting it to +aaa*,-bbb*,+ccc*,+*, means that an index that starts with aaa it will be automatically created, an index with bbb prefix will not be automatically created, ccc prefix will be automatically created, and anything else (+*) is allowed.