Implement serializer

[brusherru]

Implement serializer classes.
For a beginning just Serializer (abstract) and LocalStorageSerializer.

Serializer works only with Services and works with serverState (composition of all service states).

[brusherru]

Class diagram:
"+" — public property / method
"-" — private property / method
"#" — protected property / method

Serializer

- serverState : ServerStateObject — stores serverState, that loaded from resource
- currentState : ServerStateObject — current serverState (immutable), that will be changed by Services and could be saved to resource
+ hasChanges() : Boolean — method that diffs serverState and currentState. Maybe useful to prevent unnecessary saves, disable "save" button and etc
+ load( ids: Array<number> ) : ServerStateObject — method that will be called by Application (or another head class) to load ServerState for all opened patches
+ get( serviceName: string, id?: number ) : ServiceStateObject — method that will be called by Services to load serviceState (return only part of ServerState)
+ save() : ResponceObject — save json data to resource
# _store(response: ResponseObject) : ResponseObject — save json data to resource (contains logic where to save and how)
# _restore(response: ResponseObject) : ResponseObject — loads json data from resource (called by getPatches)
- _fromJSON() : Object — parse json data into object ()
- _toJSON() : String - JSON.stringify(object)
- _createResponse() : ResponseObject — creates empty response with status pending

ResponseObject

status: ResponseStates — enum ResponseStates { pending, success, fail }
data: any — could contain object with some data, error message / error number and etc

[nkrkv]

No longer relevant