Updated travis.yml to generate OSx pre-built binaries.
Merge branch 'pre-built-binaries' into osx-node-pre-gyp

Include latest changes to the pre-built-binaries branch.
Merge pull request #320 from hybridgroup/osx-node-pre-gyp

Osx node pre gyp.
Merge branch 'osx-node-pre-gyp' of github.com:voodootikigod/node-serialport into osx-node-pre-gyp
Merge branch 'master' into osx-node-pre-gyp with updated secure env
vars and [publish binary].
Merge branch 'osx-node-pre-gyp' into fix-osx-binaries-v1.4.6

Conflicts:
	.travis.yml