use cached dependencies for os x build
fix downloading
install awscli on osx
Merge pull request #428 from mapbox/cache-osx-dependencies

Cache OS X dependencies
fix warnings
bump cocoa bindings
use texsubimage2d to avoid texture memory reallocation
Merge pull request #430 from mapbox/fix-build-warnings

Fix build warnings
refs #431: bring back Travis Bash strictness
Merge pull request #432 from mapbox/travis-bash-strict

refs #431: bring back Travis Bash strictness
update mapbox/variant
Merge pull request #433 from mapbox/update-variant

Update variant implementation
Merge pull request #429 from mapbox/texture-updates

Use texSubImage2D to avoid texture memory reallocation
add missing git fetch for mapnik-packaging

When there is a local mapnik-packaging repo, 
git checkout a future commit requires a git fetch
bring back Linux tests in separate script
rename tests script
Merge pull request #435 from mapbox/separate-tests-script

bring back Linux tests in separate script
Rename existing interpolate -> resample
Consolidate duplicate interpolation definitions

While here, do not interpolate style properties that
are not transitionable. The previous behavior was to
switch from old to new value halfway through the transition;
now the new value is used immediately, as in JS.
Use float for pixelRatio