Build, package and publish pre-compiled binary versions for serial port using node-pre-gyp

Add fallback to buil to node-pre-gyp install command, in case remote binary download fails.

Added travis automated binary build, to generate and pubslish the serialport packages.

Publish binaries adding `[publish binary]` to a commit message or by
adding a release tag.

Add travis automated build for x86 32 bit binaries.[publish binary]
Updated travis.yml to generate OSx pre-built binaries.
Added support for AppVeyor.

1. Created new appveyor.yml configuration file.
2. We are now packaging and publishing windows 32bit version of the
binary.
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.