initial version of boost-system
allow setting mason dir
boost: use host CC to avoid breaking on cross compile (android)
Boost 1.57.0 script
Update hash
Make dir first
Recursive mkdir
Add include flag
Use BOOST_ROOT
No quotes
add travis file
exit with correct codes
allow setting MASON_HEADER_ONLY=true for header-only builds

these "builds" are not in separate platform subfolders as they are shared across all platforms
do a header-only build of boost headers and only unzip the ones we need
don't check for lib files on header only installs
Merge branch 'boost-1.57.0' of https://github.com/mapbox/mason
Merge branch 'master' of https://github.com/mapbox/mason