chore: karma with JS, Dart

Note: karma with dart is still not working
because of how `karma-dart` loads `package:…` dependencies.

Usage:
```
karma start karma-js.conf.js
karma start karma-dart.conf.js
```

Make sure to set `DARTIUM_BIN` env variable.

Refactors `js2dart`:
- live outside of the traceur module (`tools/js2dart/index.js`)
  so it can be reused by gulp and karma
- automatically build the sources in memory,
  so that `js2dart` can be used without running `gulp build` first
- provide a way to specify the moduleName of a compilation run
  independently of the input filename. This helps error messages
  and source maps (not yet enabled) to report the correct file name

Changes project setup:
- add module `test_lib` that contains the primitives for tests
  (e.g. `describe`, `it`, …)
- clean up some sources that had errors in them
- module names in transpiled js and dart files don’t contain
  `lib`, `test` nor `src` any more (e.g. `di/di`).

modules/change_detection/pubspec.yaml

@@ -3,4 +3,5 @@ environment:
   sdk: '>=1.4.0'
 dependencies:
 dev_dependencies:
-  unittest: '>=0.10.1 <0.12.0'
+  test_lib:
+    path: ../test_lib

modules/core/pubspec.yaml

@@ -9,4 +9,5 @@ dependencies:
   facade:
     path: ../facade
 dev_dependencies:
-  unittest: '>=0.10.1 <0.12.0'
+  test_lib:
+    path: ../test_lib

modules/core/src/compiler/compiler.js

@@ -1,4 +1,4 @@
-import {Future} from 'facade/lang';
+import {Future, Type} from 'facade/lang';
 import {Element} from 'facade/dom';
 import {ProtoView} from '../view/proto_view';
 import {TemplateLoader} from './template_loader';

modules/core/test/compiler/compiler_spec.js

@@ -1,6 +1,7 @@
-import {describe, id} from 'spec/spec';
+import {describe, id} from 'test_lib/test_lib';
+import {Compiler} from './compiler';
 
-function main() {
+export function main() {
   describe('compiler', () => {
     it('should hello', () => {
       print('I am working');

modules/di/pubspec.yaml

@@ -5,4 +5,5 @@ dependencies:
   facade:
     path: ../facade
 dev_dependencies:
-  unittest: '>=0.10.1 <0.12.0'
+  test_lib:
+    path: ../test_lib

modules/di/src/key.js

@@ -0,0 +1,3 @@
+export class Key {
+
+}

modules/di/src/module.js

@@ -1,5 +1,6 @@
 import {Type} from 'facade/lang';
 import {Map, MapWrapper wraps Map} from 'facade/collection';
+import {Key} from './key';
 
 /// becouse we need to know when toValue was not set.
 /// (it could be that toValue is set to null or undefined in js)

modules/examples/pubspec.yaml

@@ -3,4 +3,5 @@ environment:
   sdk: '>=1.4.0'
 dependencies:
 dev_dependencies:
-  unittest: '>=0.10.1 <0.12.0'
+  test_lib:
+    path: ../test_lib

modules/facade/pubspec.yaml

@@ -3,4 +3,5 @@ environment:
   sdk: '>=1.4.0'
 dependencies:
 dev_dependencies:
-  unittest: '>=0.10.1 <0.12.0'
+  test_lib:
+    path: ../test_lib

modules/test_lib/pubspec.yaml

@@ -0,0 +1,6 @@
+name: test_lib
+environment:
+  sdk: '>=1.4.0'
+dependencies:
+dev_dependencies:
+  guinness: ">=0.1.5 <0.2.0"

modules/test_lib/src/test_lib.dart

@@ -0,0 +1 @@
+export 'package:guinness/guinness.dart' show describe, it, beforeEach, afterEach, expect;

modules/test_lib/src/test_lib.es6

@@ -0,0 +1,8 @@
+export var describe = window.describe;
+export var it = window.it;
+export var beforeEach = window.beforeEach;
+export var afterEach = window.afterEach;
+export var expect = window.expect;
+
+// To make testing consistent between dart and js
+window.print = window.dump || window.console.log;