0.8.6

Breaking:

• change the format of /valid and /cache responses

Features:

• add a script to warm the cache (make warm)
• add CACHE_DIRECTORY and CACHE_PERSIST environment variables to manage cache persistence
• reduce datasets library log level

Fixes:

• fix parsing of boolean env vars
• exceptions are now cached by the memoize decorator

Internals:

• add a test about the generation of cache reports