Add setting to select previous entry behavior

[chrishunt]

👀 @r00k

In the last week, we've received two emails from folks who would prefer to see the behavior we removed in #155. We may add a setting for this so everyone is happy.

Number 1:

I can't seem to figure out your methodology for sending me messages. I seem to be getting random notes about random things. I imported my data from oh life so I imagine I have plenty of data.

What i got today was from august 31, 2013. which i can't really frame as well.

Ideally, i'd like it to be 1 year ago, then, if no data was there, then 1 month ago, then 1 week ago, then 1 day ago, then... who knows.

But at least it's more frameable to see how far you've come, or how long something was. Seeing (over two years ago) really isn't all that helpful and definitely makes it less cool.

Number 2:

Trailmix (and before that, Oh Life) used to send me my daily question accompanied by my entry from the same date of the previous year. However in the last few months, you seem to have changed your algorithm and have increased the randomness. It is much more meaningful to me to read what happened on March 11th of last year -- or even the year before or the year before that -- rather than some random date.

[r00k]

I'd be open to adding this option.

Looks like people want 1 year ago to take priority over other anniversaries, which is the opposite of how we did it, I think.