Katip + Aeson 2.0.0.0 Compatibility

[tbidne]

Background

The motivation for this PR is #128, to add aeson-2 compatibility. To sum up, the plan was:

1. Add individual stack.yamls to each sub-project.

For the projects that can be upgraded (katip, katip-datadog, katip-logzio):

2. Add CPP for aeson 1/2 compatibility.
3. Pin to aeson-2.0.1.0.

Changes

This PR completes 1 for all projects and 2+3 for katip.

I have 2+3 for the other projects implemented on another branch (you can see the diff here) because I figured it might make sense to merge them separately since katip-datadog and katip-logzio will have to pin the new katip-0.8.7.0 too.

The changes are pretty mechanical, simply (un)wrapping Key to Text. The relevant new aeson modules are Data.Aeson.KeyMap and Data.Aeson.Key.

Tests

You'll notice I had to add new golden files for the tests (see katip/test/Katip/Tests/Scribes/Handle.hs). diff Handle-text.golden Handle-text-aeson2.golden highlights the last two lines. Note that the order of the last few keys (sub, text, num, float) has changed:

< [2016-06-12 12:34:56][foo][Info][example][PID 7331][ThreadId 1337][sub:null][text:][num:0][float:0] message
< [2016-06-12 12:34:56][foo][Info][example][PID 7331][ThreadId 1337][sub.note.deep:some note][text:note][num:10][float:5.5] message
---
> [2016-06-12 12:34:56][foo][Info][example][PID 7331][ThreadId 1337][float:0][num:0][sub:null][text:] message
> [2016-06-12 12:34:56][foo][Info][example][PID 7331][ThreadId 1337][float:5.5][num:10][sub.note.deep:some note][text:note] message

I'm not very familiar with how katip orders these last few keys, but I'm guessing this ordering implicitly comes from aeson, hence the change. Let me know if this is a problem.

The json file, Handle-text.golden, also had the order changed, but the json is structurally identical. I whipped up this gist you can use to verify they're the same.

---

Let me know if you have any questions, requests, etc. Thanks!

[MichaelXavier]

This looks great! Thank you!

[tbidne]

Excellent, thank you for the quick turn-around! Would you like a second PR for katip-datadog and katip-logzio?

[MichaelXavier]

Sure, if you're feeling up to it!