Fix the metadata and appId options assignments

[alexgerv]

Currently, the appId is not being set correctly and was always defaulting to the default ID because the option was undefined.
The metadata was also affected by the same issue, and was fixed by PR #30

The proposed fix is to populate the options before calling super. Let me know what you think.

[drexseoj]

We like to vote for this issue. as we can not use our own receiver unless we modify the module.

[alexgerv]

@benjipott any comment on the PR ? Would you have another approach ?

[Fenny]

@benjipott hello?

[DoomTay]

Curiously, when I tried running this on a local HTML file or from a local server or even CodePen, the Chromecast button wouldn't show up, though it works just fine when running off a userscript.

Looking at it further, it seems the cause is that something about populating the options before calling super causes the receiverListener to fire only once.