Open google doc issue 27: Caching

[wvdemeer]

Below is a literal copy of google doc issue 27:

1. Caching. -- option listresources cached or not -- github proposal

Jordan: The current OpenSFA implementation offers the ability to use a cached version of the RSpecs through a proper setting in the options.

Oscar: The caching option is useful but how is it being implemented? what is the cache refreshing period? Could we use some kind mechanism to decide when refresh the Caché? (i.e. offer the hashcode of the Advertisement RSpec somewhere)

Note: Talk about options in API calls in more details: which ones are proposed, how this list can e extended by the testeds.