The HTTP cache for the API can now be disabled via the

--disable-caching command line argument. It can also be moved to an

arbitrary location with --cache-location FILE or created in memory

with --in-memory-cache. This behaviour is also available to consumers

of the API via the RBClient. The allow_caching, cache_location,

and in_memory_cache key word arguments can be used for this.

Unit tests passed.
Ran the following commands:

rbt status --debug --disable-cache
rbt status --debug --in-memory-cache
rbt status --debug --cache-location /tmp/cache

The debugging information indicated the correct behaviour was taking

place in each instance.