Switch deployment to use Grunt

[alexanderdean]

Workflow:

1. S3: upload sp.js to s3://xxx/{full-version}/sp.js (e.g. .../0.14.0/sp.js)
2. S3: upload sp.js to s3://xxx/{MAJOR-version}/sp.js (e.g. .../0/sp.js)
3. CloudFront: invalidate object from 2

See:

• https://github.com/pifantastic/grunt-s3
• https://github.com/mllrsohn/grunt-invalidate-cloudfront

[alexanderdean]

Done in 0.14.0, closing.