accessPolicy: Implement Put, Get, Delete access policy.
This patch implements Get,Put,Delete bucket policies
Supporting - http://docs.aws.amazon.com/AmazonS3/latest/dev/access-policy-language-overview.html
Currently supports following actions.
"*": true,
"s3:*": true,
"s3:GetObject": true,
"s3:ListBucket": true,
"s3:PutObject": true,
"s3:CreateBucket": true,
"s3:GetBucketLocation": true,
"s3:DeleteBucket": true,
"s3:DeleteObject": true,
"s3:AbortMultipartUpload": true,
"s3:ListBucketMultipartUploads": true,
"s3:ListMultipartUploadParts": true,
following conditions for "StringEquals" and "StringNotEquals"
"s3:prefix", "s3:max-keys"