Issue #22: Add a test for the can_cache option.
Merge pull request #23 from deviantintegral/can-cache-test

Issue #22: Add a test for the can_cache option.
Fix not adding timezone to dates.
Merge pull request #24 from deviantintegral/missing-date-gmt

Fix not adding timezone to dates.
Issue #22: Add $defaultTtl to CacheStorage constructor.
Merge pull request #25 from deviantintegral/cache-set-ttl

Issue #22: Add setDefaultTtl() to CacheStorage.
Fix stale-if-header not being added to max-age.
Merge pull request #27 from deviantintegral/stale-if-header-ttl

Fix stale-if-header not being added to max-age.
fix error caches responses for without vary headers
add a check returned object from the cache if it is not an array, then return an empty array
fix missing date gmt
remove the body from these requests if we're not asserting anything with them