Update Rakefile

Creating two more emails so that the 2/3 condition for "Old Friend" can be satisfied.
If I understand what's happening here, the `MakeOldFriends` code is saying:

* create an email / reply thread 18 weeks ago
* create an email / reply thread 20 weeks ago
* create an email / reply thread 22 weeks ago
* etc...

If we pass Sue and Joe to the `MakeOldFriends`, it should satisfy the 'old friends' requirement, right?

* Sue has sent 3 or more emails to Joe (ever) - √ - 18, 20, 22, 24, 26 and 28 weeks ago
* Joe replied to 2 out of every 3 emails - √ - in this case, he would have replied to 100% of the emails

I feel like I'm missing something (or maybe the readme was really unclear).  Have you posted a solution to it yet?