add more fiddle hash checks

Convert some of bookmaker to use real json instead
of rolling its own. Also check to see if all
hashes are read.

TBR=jcgregario@google.com

Docs-Preview: https://skia.org/?cl=142166
Bug: skia:8151
Change-Id: Ib35ecd69648faec3522903e0b552d37b04b73f8b
Reviewed-on: https://skia-review.googlesource.com/142166
Commit-Queue: Cary Clark <caryclark@skia.org>
Auto-Submit: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@skia.org>
7 files changed