Add Scala.js test suite

Complete with Jasmine runner, console reporter and 72 specs.
It currently has two failing specs.

```
[info] Starting Scala.js test suite
[info]
[info] Scala.js compiler regression tests
[info]   Wrong division conversion (7 / 2.0) - #18
[info]   js.String + js.String is ambiguous - #20
[info]   Abort with some pattern match guards - #22
[info]   Bad encoding for characters spanning 2 UTF-16 chars - #23
[info]   String concatenation with null - #26
[info]
[info] java.lang.Object
[info]   should provide `equals`
[info]
[info] java.lang.Integer
[info]   should provide `reverseBytes` used by scala.Enumeration
[info]   should provide `bitCount` used by Map
[info]
[info] java.lang.String
[info]   should respond to `length`
[info]   should respond to `intern`
[info]   should respond to `equals`
[info]   should respond to `compareTo`
[info]   should respond to `isEmpty`
[info]   should respond to `contains`
[info]   should respond to `startWith`
[info]   should respond to `endsWith`
[info]   should respond to `indexOf`
[info]   should respond to `lastIndexOf`
[info]   should respond to `toUpperCase`
[info]   should respond to `toLowerCase`
[info]   should respond to `charAt`
[info]   should respond to `codePointAt`
[info]   should respond to `subSequence`
[info]   should respond to `replace`
[info]   should respond to `matches`
[info]   should respond to `split`
[info]
[info] java.util.Arrays
[info]   should respond to `sort` for Int
[info]   should respond to `sort` for String
[info]   should respond to `fill` for Int
[info]
[info] scala.scalajs.js.Array
[info]   should provide implicit conversion from js.Array to ArrayOps - String
[info]   should provide implicit conversion from js.Array to ArrayOps - Int
[info]     ☹ java.lang.ClassCastException: 7 is not an instance of java.lang.Integer
Add Scala.js test suite
[info] 1 of 3 failed
[info]
[info] scala.scalajs.js.Dictionary
[info]   should provide equivalent of JS for-in loop of {} - #13
[info]   should provide equivalent of JS for-in loop of [] - #13
[info]
[info] scala.scalajs.js.Dynamic
[info]   should workaround Scala 2.10 issue with implicit conversion for dynamic fields named x - #8
[info]   should allow instanciating JS classes dynamically - #10
[info]
[info] scala.Enumeration
[info]   requires reflection for populating the name map
[info]     ☹ TypeError: Cannot find function getDeclaredFields__ALjava_lang_reflect_Field in object class scala.EnumerationTest$$anonfun$1$$anonfun$apply$mcV$sp$1$HelpLevel$2. in /opt/scala-js/test/target/streams/test/externalDependencyClasspath/$global/package-js/extracted-jars/scalajs-library_2.10.jar--6a954585/scala/0002-Enumeration.js (line 125)
[info] 	at /opt/scala-js/test/target/streams/test/externalDependencyClasspath/$global/package-js/extracted-jars/scalajs-library_2.10.jar--6a954585/scala/0002-Enumeration.js:125 (anonymous)
[info] 	at /opt/scala-js/test/target/streams/test/externalDependencyClasspath/$global/package-js/extracted-jars/scalajs-library_2.10.jar--6a954585/scala/0003-Enumeration$$anonfun$scala$Enumeration$$nameOf$1.js:10 (anonymous)
[info] 	at /opt/scala-js/test/target/streams/test/externalDependencyClasspath/$global/package-js/extracted-jars/scalajs-library_2.10.jar--6a954585/scala/0003-Enumeration$$anonfun$scala$Enumeration$$nameOf$1.js:14 (anonymous)
[info] 	at /opt/scala-js/test/target/streams/test/externalDependencyClasspath/$global/package-js/extracted-jars/scalajs-library_2.10.jar--6a954585/scala/collection/0001-MapLike$class.js:20 (anonymous)
[info] 	at /opt/scala-js/test/target/streams/test/externalDependencyClasspath/$global/package-js/extracted-jars/scalajs-library_2.10.jar--6a954585/scala/collection/0004-AbstractMap.js:20 (anonymous)
[info] 	at /opt/scala-js/test/target/streams/test/externalDependencyClasspath/$global/package-js/extracted-jars/scalajs-library_2.10.jar--6a954585/scala/0002-Enumeration.js:138 (anonymous)
[info] 	at /opt/scala-js/test/target/streams/test/externalDependencyClasspath/$global/package-js/extracted-jars/scalajs-library_2.10.jar--6a954585/scala/0003-Enumeration$Val.js:17 (anonymous)
[info] 	at /opt/scala-js/test/target/streams/test/externalDependencyClasspath/$global/package-js/extracted-jars/scalajs-library_2.10.jar--6a954585/scalajs-corejslib.js:574 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/scala/0004-EnumerationTest$$anonfun$1$$anonfun$apply$mcV$sp$1.js:22 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/scala/0004-EnumerationTest$$anonfun$1$$anonfun$apply$mcV$sp$1.js:17 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/scala/0004-EnumerationTest$$anonfun$1$$anonfun$apply$mcV$sp$1.js:25 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/scala/scalajs/test/0002-ScalaJSTest.js:17 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/jasmine.js:1087 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/jasmine.js:2119 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/jasmine.js:2072 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/jasmine.js:2399 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/jasmine.js:2119 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/jasmine.js:2072 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/jasmine.js:2544 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/jasmine.js:2119 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/jasmine.js:2072 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/jasmine.js:2166 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/jasmine.js:825 (anonymous)
[info] 	at /opt/scala-js/test/target/scala-2.10/test-classes/main.js:27
[info] 1 of 1 failed
[info]
[info] 72 spec(s), 2 failure(s) in 3.308s.
```