Add handling for tile zoom/x/y and bbox params in posts/geojson api

* Convert tile values to bounding box
* Add filtering to posts controller for bounding boxes
* Accept ?bbox= param for /posts
* Allow unlimited posts returned from /posts api controller so that
  geojson can return EVERYTHING at once
* Only handle tile values for posts collection not individual posts
Return all point attributes in GeoJSON

Checks all possible point attributes and returns them in geojson
* If just 1 value it is returned as a point
* If multiple its returned as a GeometryCollection
* If no geometries found the post is skipped
Return all point or geometry attributes in geojson

* Search both geometry and point attributes
* Use gisconverter to decode WKT to GeoJSON