add support for not signed request headers, http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectPUT.html
Update README.md
remove function merge() and use extend() instead
Merge pull request #40 from dconnolly/master

Export Evaporate by detecting module.exports or window.
resolve conflict with the upstream's master branch
Update README.md
Merge pull request #39 from uqee/master

Add support for custom request headers which should not be signed by the secret key
Merge pull request #42 from uqee/angular-example

Update README.md