def store(type, hash, file)
      raise Dis::Errors::ReadOnlyError if readonly?
      store!(type, hash, file)
    end
def store(type, hash, file)
      raise Dis::Errors::ReadOnlyError if readonly?
      store!(type, hash, file)
    end
Stores a file.

   hash = Digest::SHA1.file(file.path).hexdigest
   layer.store("documents", hash, path)

 Hash must be a hex digest of the file content. If an object with the
 supplied hash already exists, no action will be performed. In other
 words, no data will be overwritten if a hash collision occurs.

 Returns an instance of Fog::Model, or raises an error if the layer
 is readonly.