Cache enhancement

Based on the discussion here: https://github.com/developmentseed/scoreboard/pull/468#discussion_r370795638

We should have an enhancement to the memory-cache and how it is used by the different processes. This could be done in a couple of ways:

1. Wrap memory-cache to allow for lazy loading in case of a cache miss.
2. Run processes through a "cache initializer" first that loads the cache using the database settings and then kicks off the subprocess