Refresh layout of AppDetails screen

This change primarily affects the AppDetails links section to make them easier to click. It also strips down the UI a bit to provide a cleaner interface as well as some modest Material Design tweaks.

Fixes #389 (closed).

Also fixes an unreported issue where the permissions list would be blank if the app only requested the root permission on devices which no longer support this.

The most significant change is arguably removing the expand/collapse functionality around the links and permissions UI elements. I think personally this kind of UI behavior is a bit of an anti-pattern as it clutters up the UI visually and doesn't provide much if any real utility to the user. Also, given the background and context of the app, I would argue that the links (especially to the source code and website) should have high visual priority as well as the permissions the application requests. I know I personally very commonly click on these before deciding to install any given app.

It's not perfect, and I would like to do more eventually, but I tried to refrain from making too many or too drastic of changes to the existing design for now.

before	after

link touch target