Ken Walters

V4 signer should encode space in query params with "%20" rather than "+"

2

Per #242, the v4 signer should encode a space in query params with a "%20" rather than "+" when building the canonicalURI. http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html In [aws/sign.go#L246](https://github.com/crowdmob/goamz/blob/69802b744811077488714d3d2f7b34985987df98/aws/sign.go#L246) and [aws/sign.go#L251](https://github.com/crowdmob/goamz/blob/69802b744811077488714d3d2f7b34985987df98/aws/sign.go#L251) the query string...