Adding synonyms filter to pelias

![](http://giant.gfycat.com/SardonicFlakyBrontosaurus.gif)

* [x] Add analyzer to ```settings.js```
* [x] Add analyzer-related tests in https://github.com/pelias/schema/blob/master/test/settings.js
* [x] Determine location of ```synonyms.txt``` (in my system, the only place I've made it work with has been ```/usr/local/Cellar/elasticsearch/1.2.1/config/analysis```)
* [x] Hook pelias-synonyms to generate the file and plug it directly to ES