Clear out previous generation cached data from Redis

[wincent]

Can do it manually, but would be nice to make this part of the deploy somehow.

Less worried about memcached as it should evict any stuff that hasn't been used recently.

[wincent]

Manual way:

# Given the cache-breaker is up to 6:
redis-cli --scan --pattern "masochist:[12345]:*" | xargs -L 100 redis-cli DEL

One of many alternatives suggested here.

Was able to drop (tiny) Redis db at /var/redis/$REDIS_PID/dump.rdb from 3.7M to 1.2M.

Looks like something that can be automated easily enough, but may not need to bother with it.