use /v4, use access_token for tilejson requests
add close button to popups
Merge pull request #421 from mapbox/close-button

add close button to popups fixes #365
fix baselayer toggle
remove unecessary line
Merge pull request #422 from mapbox/fix-baselayer

fix baselayer toggle, fixes #420
Merge branch 'master' into authed_tiles
Mock the mapbox tile API to handle auth requests.
Add error case tests for missing oauth creds.
Fix source fail test and only test at the source level.
Use https
Merge pull request #413 from mapbox/authed_tiles

Use authed requests for mapbox tiles (v4)
Merge branch 'master' into mapnik-omnivore