Add 'id' attribute to ViewDescriptor

[rickbrew]

If the layout XML looks like this:

<Button android:id="@+id/apod_btn" ...

Then we should show it similarly in the elements tab, e.g.

<button id="@+id/apod_btn" ...

View.toString() already does this, so adapting from that should be straightforward.

[jasta]

Interesting, this was not automatically closed. Apparently, the commit itself must have this information in it, not just the pull request summary. Recommend spending more time up front to format the commit message as a result.