Paperclip s3

Support for attatchments with option to store on s3.

Default storage is local filesystem.
To store on s3 you need to set these env variables:
PAPERCLIP_STORAGE = s3 (set back to filesystem to use local again)
AWS_BUCKET = "your bucket name"
AWS_ACCESS_KEY_ID = "your access key id"
AWS_SECRET_ACCESS_KEY = "your secret access key"