add ignore module formatter - closes #119

lib/6to5/modules/ignore.js

@@ -0,0 +1,21 @@
+module.exports = IgnoreFormatter;
+
+function IgnoreFormatter(file) {
+
+}
+
+IgnoreFormatter.prototype.import = function (node, nodes) {
+
+};
+
+IgnoreFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
+
+};
+
+IgnoreFormatter.prototype.export = function (node, nodes) {
+  nodes.push(node.declaration);
+};
+
+IgnoreFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
+
+};

lib/6to5/transform.js

@@ -117,6 +117,7 @@ transform.transformers = {
 
 transform.moduleFormatters = {
   common: require("./modules/common"),
+  ignore: require("./modules/ignore"),
   amd:    require("./modules/amd"),
   umd:    require("./modules/umd")
 };