Fix search

I installed Elasticsearch v1.4.1 and composer installed elasticsearch/elasticsearch v1.3.1.
But search results are always `There are no search results`, after I run `search-tasks.php`.

So I updated the code, and changed how to search because original code is for forum.

**Original code**: search `title = $q and content = $q`, if fails search `title = $q`, and results are filtered some conditions (a post has good karuma or replies or is accepted answer?)
**My code**:  search `title = $q or content = $q`

I don't know Elasticsearch well. So my code is probably not perfect.