Cache Dates

[jonthegeek]

As a wikimorphemes user, I'd like to specify how old I'm ok with the lookup being, so that I can only update if I haven't updated this word (or piece of a word) in a while.

At the same time, 'cuz otherwise that's kinda pointless:
As a wikimorphemes user, I'd like to update the lookup as I use wikimorphemes, so that I don't hit the API repeatedly for the same word if I have it recent enough.

[jonthegeek]

Ended up removing this from that PR. We'll decide if this is worth doing.