Add 3 new routes to manage the cache
Add 3 new routes to manage the cache

* /api/cache/purge - clears all cached data (useful when testing or
after adding more data)
* /api/cache/stats - returns results of memcached stats comman
* /api/cache/build - builds 5 commonly needed caches, list could expand
as needed (will take some time…)

ahoarfrost/metaseek,ahoarfrost/metaseek,ahoarfrost/metaseek