Fix scrollbars overlapping content.

- Scrollbars respect padding by default, turn that off.
- Also unify grid views, so we don't have to edit that many files again.
- Remove center gravity from show grid (why was this set?).
Set SDK and build tools version in root gradle file.

- Also move support lib and okhttp, which is used by libraries up there
so we can ensure the same version.
Fix library tab not displaying show overviews.

- Use extended version of user/library/shows endpoint.