Use API v4 and access tokens
Merge branch 'master' into access_token

Conflicts:
	.gitignore
move to per-map access token
bump Cocoa
cleanup
move Linux & OS X to per-map access tokens
flesh out access token README docs
Merge branch 'master' into access_token

Conflicts:
	src/map/source.cpp
read access token from environment
read access token from environment
update docs
[skip ci]
Merge pull request #351 from mapbox/access_token

Use API tokens and v4 vector tile endpoint
move sprite class to map directory
change line width and add line-width test
cleanup
report fixture request errors
allow specifying a base parameter for exponential functions

refs mapbox/mapbox-gl-style-spec#4
remove *-enabled

refs mapbox/mapbox-gl-style-spec#94
convert stylesheet to use the correct stop values
[skip ci]
break out StyleSource from Source, move getActiveSources and updateSources into Map::Map