Storage module description

Module provides an access to persistent storage. Plugins can store data in key/value format. Each plugin has its own volume in storage and implementation must guarantee no clashes between key‘s in different volume‘s As long as one plugin can use other ones and so on forming calling tree an implementation must use volume for the root plugin in this tree. It means that if plugin is meant to be used as library it will have separate storage for every topmost user. However, plugins in one calling tree should take responsibility to prevent key collision in one volume.