added copy_to method for RubyBox::File

added copy_to method to RubyBox::File

RubyBox::File.copy_to( FolderID, name<optional> )

Could easily change this to accept the new remote file path as a parameter instead of the folderID and optional name. Then parse the new path into the new name and make an additional call to do the folderID lookup. This accomplished what i need though.