4 expose all overheards with json

Fixes #4 

This is a lovely example of how everyone is wrong all the time and that's ok.

I [wrote one commit](https://github.com/codeunion/overheard-server/commit/d8dd94f910904de4b073174451e9365a2234f623) where I *thought* I was fixing a random test failure. It turns out that [I was wrong](https://github.com/codeunion/overheard-server/commit/a61a2743299764b633608243ba842754be148095).

This is why debugging is such a hugely important skill.

This also has two seperate refactor commits. One where I [write a helper to respond with json](https://github.com/codeunion/overheard-server/commit/a96f661e3d5627cb5643f5cca6733d375dcb9738) and another where I [add a bit of sugar](https://github.com/codeunion/overheard-server/commit/607489296c25fe25873615af31529858d833753c) when determining what data format to send back.

An important thing to note is that I did these refactors *after* I had gotten the code working. This follows the good old programmer advice of: **First Make it Work, Then Make It Pretty**