Return object from defineProperty

Fixes #398, returns the given object from defineProperty to match spec definition.

Review URL: https://github.com/google/traceur-compiler/pull/399

Closes #399, closes #398.
Fix issues related to System.resolve and System.normalize on Node

1. The module loader was setting the referrer even for `type == 'module'`. The code gen for module is surrounded by registerModule which now resolves the `System.set`, causing us to do a double resolve. This works fine in a browser because we have an absolute URL but in Node.js it is relative paths.

2. The test used window.location.href or __filename. The file name path is not working well. I change the test to not depend on the environment.

Fixes #396

Review URL: https://github.com/google/traceur-compiler/pull/400

Closes #400, closes #396.
Remove module definition

This removes inline module definitions

```js
module 'm' {
  ...
}
```

Only external modules are supported.

Now that inline modules are gone a lot of simplifications were possible.

Review URL: https://github.com/google/traceur-compiler/pull/401

Closes #401.
Remove .js from ImportSpecifiers

    find src | xargs grep -l "from\s*'.*\.js';$" | xargs sed -i -e "/from\s*'.*\.js';$/s/\
    .js';$/';/"
Increment NPM version
Remove support for import *

Fixes #387

Review URL: https://github.com/google/traceur-compiler/pull/402

Closes #402, closes #387.
Change how we handle relative paths for System.get/set

These are now always relative to baseURL. The code gen now updates
the relative paths as needed.
Merge pull request #408 from arv/simplify-system-get-set-resolve

Change how we handle relative paths for System.get/set
Add test node that runs in a new context

This fixes a bad dependency for generated code for the super
transformer which made it depend on runtime.js.

Review URL: https://github.com/google/traceur-compiler/pull/409

Closes #409.
Bootstrap System.get/set in runtime.js

We now set up a very rudimentary `System.get` and `System.set` as well as `registerModule` in runtime.js. This does not do any name resolution but that is sufficient to at least work with the output generated by the command line compiler.

This also adds a node test that compiles a js file with an import, prepends runtime.js and the executes that in a new context.

Review URL: https://github.com/google/traceur-compiler/pull/410

Closes #410.
Increment NPM version to 0.0.6
Removes private name syntax / at-name

Fixes #403

Review URL: https://github.com/google/traceur-compiler/pull/411

Closes #411, closes #403.