Properly crash the app if transformation throws, add missing tests.
Merge pull request #711 from square/dimitris/crash-on-bad-transform

Properly crash the app if transformation throws, add missing tests.
Sneaky rethrow on request creator id.
Merge pull request #712 from square/dimitris/sneaky-rethrow

Sneaky rethrow on request creator id.
Shutdown should close disk cache.
Merge pull request #713 from square/dimitris/shutdown-cache

Shutdown should close disk cache.
Add 'noPlaceholder' for not setting or clearing target.