function BaseServer(config) {
        this._baseUrl       = config.baseUrl;
        this._root          = config.root;          // ProjectManager.getProjectRoot().fullPath
        this._pathResolver  = config.pathResolver;  // ProjectManager.makeProjectRelativeIfPossible(doc.file.fullPath)
        this._liveDocuments = {};
    }
Base class for live preview servers

Configuration parameters for this server:
- baseUrl      - Optional base URL (populated by the current project)
- pathResolver - Function to covert absolute native paths to project relative paths
- root         - Native path to the project root (and base URL)

@constructor
@param {!{baseUrl: string, root: string, pathResolver: function(string): string}} config