Implemented abstract prefixing methods
Make Local use the abstract prefixing functions
Abstract path prefixing implemented for Dropbox
Implemented abstract prefixing for AwsS3
Implemented abstract prefixing for Rackspace
Added prefix for webdav
Added path prefixing to Zip
Added getPathPrefix to fetch root of an adapter
Revert "Implemented abstract prefixing for AwsS3"

This reverts commit 693eb2546c20ad24a668759777bb2c94519ed4e5.
Merge branch 'master' into feature-path-prefix
Merge branch 'feature-path-prefix'