Support for virtual host style s3 uris

[jcrowgey]

Amazon has published some guidelines which suggest migrating away from path-style s3 uris:

https://aws.amazon.com/blogs/aws/amazon-s3-path-deprecation-plan-the-rest-of-the-story/

go-getter seems to only support path-style, however:

go-getter/get_s3.go

Line 205 in 30a49e4

conf.S3ForcePathStyle = aws.Bool(true)

Or, perhaps I'm missing something, since I do see that virtual-host style uris are delectable:

go-getter/detect_s3.go

Line 53 in 30a49e4

func (d *S3Detector) detectVhostStyle(region, bucket string, parts []string) (string, bool, error) {

[picatz]

Should be fixed with #283