Use Skylight instead of New Relic

This is just an idea. Feel free to :-1: 

I had a look at New Relic this afternoon and it was pretty confusing and (surprisingly) slow. I appreciate the simplicity of this (trailmix on staging):

![skylight](https://cloud.githubusercontent.com/assets/65323/4568905/06f894e6-4f41-11e4-88c3-90c8207b2fae.png)

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![skylight2](https://cloud.githubusercontent.com/assets/65323/4568912/397b269a-4f41-11e4-814c-2f2bcde3f3ff.png)