add allow-overlap and ignore-placement for text & icon
Merge pull request #64 from mapbox/placement

Add allow-overlap and ignore-placement for text & icon
clarify wording
swap hipchat token
doc property cleanup
update $type filter values
update package version
add default for raster-fade
Merge pull request #69 from mapbox/type

Update $type filter values to match GeoJSON/VectorTile spec
add missing render_background
Merge branch 'master' into render-symbol

Conflicts:
	reference/v3.json
add icon-max-size and icon-size
properties for sdf icons