code: 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 = {};
      }
docs: 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