url argument for scaling tiles #87
show 512x512 tiles for retina display
remove scale slider from ui
adds toggle for print resolution (@4x)
point to 512 branch of tilelive-vector
update tests
first pass at downloading static map
Merge branch 'master' into 512

Conflicts:
	lib/style.js
	package.json
merge issues
remove print flag and resolution toggle
keep text for settings menu in template
remove leaflet-image & print icon
move tile resolution notice so 2x tiles do not seem to be style options
Merge pull request #399 from mapbox/512

512 tiles for retina, 256 for standard, removed scale option