Bug 929600, Bug 942355 - Update Marketplace packaged app for `origin` removal and dual SIM detection

Updated Marketplace `external-apps` packaged app with the following:

* Removed `origin` (now pulled in from our [mini manifest](https://marketplace.firefox.com/packaged.webapp)) per [bug 929600](https://bugzilla.mozilla.org/show_bug.cgi?id=929600)
    * r? @AntonioMA @jds2501
* Added detection for dual SIMs using `navigator.mozMobileConnections` per [bug 942355](https://bugzilla.mozilla.org/show_bug.cgi?id=942355)
    * r? @hsinyi @fabricedesre