Bug 1087441: Apply font fix to FMD panel header. r=arthurcc

There is only a little changes required to this file mainly on loading the AMD module defined in `/js/findmydevice.js`. The goal is to get the module defined in `js/findmydevice.js` with all of the dependent objects mocked. As now `FindMyDevice` is defined using AMD, we need to mock the dependent objects in the AMD way.

First, we create a context using `testRequire` and then define the mock objects. And then you need an map specifying the path of the mock objects. After `require('/js/findmydevice.js')` (in which we define the `findmydevice` module), we can use the object returned from `testRequire' to load the `findmydevice` module and do the following tests.

You could refer to this file[1] for details.

[1]: https://github.com/mozilla-b2g/gaia/blob/master/apps/settings/test/unit/modules/apn/apn_settings_manager_test.js#L24