cache block new endpoints: keys, values and dump
first pass at making better keys/values/dump endpoints
iterating over cache store for keys, values and dump endpoints instead of building each data structure as we go
Handling for OPTIONS requests to POST routes
Added some comments to TestCache (trigger build, good practice anyway)
Merge pull request #418 from jacqui/allow-cors

Allow OPTIONS requests on routes that currently accept POSTs
Merge pull request #415 from jacqui/cache-block

 new endpoints for cache block