Cache resources needed to sort media sizes.

- Cache media_standard_iso
- Cache labels between configuration changes (localization might
  change labels)
- Use ints instead of String's for standards
- Use HashMap instead of Array map as the lookup is faster for
  larger arrays

Fixes: 29068056
Change-Id: I027c80fac4d7e8ea6c2cac0f1a2d52b54807f5be