feat(dart/transform) Register parameter metadata information

Adds any metadata attached to a parameter to the "parameters" value
passed in to `registerType`.

For example:
`MyComponent(@Inject(Foo) foo)` generates
`"parameters": const [const [const Inject(Foo)]]`

Also reorganizes the testing code.

Closes #7

modules/angular2/test/transform/common/read_file.dart

@@ -0,0 +1,14 @@
+library angular2.test.transform.common.read_file;
+
+import 'dart:io';
+
+/// Smooths over differences in CWD between IDEs and running tests in Travis.
+String readFile(String path) {
+  for (var myPath in [path, 'test/transform/${path}']) {
+    var file = new File(myPath);
+    if (file.existsSync()) {
+      return file.readAsStringSync();
+    }
+  }
+  return null;
+}