Added SyncPackages method. Can be called by server or client connection.
In first case it begin synchronization of packages with all clients.
In second case client send message to server to begin synchronization of packages with all clients or with only this client.
Merge branch 'master' of https://github.com/VladimirPobedinskiy/Urho3D

Conflicts:
	Source/Engine/Network/Connection.h