Upgraded canvas to 2.4.1 and ejs to 1.0.0 and added support of output…

… directory for image exports

lib/image.js

@@ -49,7 +49,7 @@ var filters = {
 
 function getBoundingBox(diagram) {
     var Canvas  = require('canvas'),
-        _canvas = new Canvas(1, 1),
+        _canvas = Canvas.createCanvas(1, 1),
         ctx     = _canvas.getContext('2d'),
         canvas  = new mdjson.Graphics.Canvas(ctx);
     var boundingBox = diagram.getBoundingBox(canvas);
@@ -63,7 +63,7 @@ function getImageData(diagram, type) {
     boundingBox.expand(rectExpand);
 
     var Canvas  = require('canvas'),
-        _canvas = new Canvas(boundingBox.getWidth(), boundingBox.getHeight(), type),
+        _canvas = Canvas.createCanvas(boundingBox.getWidth(), boundingBox.getHeight(), type),
         ctx     = _canvas.getContext('2d'),
         canvas  = new mdjson.Graphics.Canvas(ctx);
 
@@ -111,6 +111,8 @@ function exportDiagramBulk(diagrams, filename, format, options, fn) {
     filename = filename || "<%=diagram.name%>.png";
     format   = format   || "png";
     options  = options  || {};
+
+    var path = filename.endsWith("/") ? filename + "<%=diagram.name%>.png" : filename;
 
     // if elements parameter is selector expression, retrieve them from Repository.
     if (_.isString(diagrams)) {
@@ -132,7 +134,7 @@ function exportDiagramBulk(diagrams, filename, format, options, fn) {
     for (var i = 0, len = diagrams.length; i < len; i++) {
         try {
             options.diagram = diagrams[i];
-            renderedFilename = ejs.render(filename, options);
+            renderedFilename = ejs.render(path, options);
             fs.ensureFileSync(renderedFilename);
             if (format === "png") {
                 exportDiagramAsPNG(options.diagram, renderedFilename);