Adding ember-cli-content-security-policy with defaults for dev

[pete-the-pete]

PR for #285

This adds the CSP without errors while working locally.

[jkleinsc]

@pete-the-pete I just ran your PR through tests, and I do see one CSP warning that I wonder if you can resolve:
[Report Only] Refused to load the image 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAAeCAYAAAAsEj5rAAAAUklEQ…EBEnMgMQ8S8+AqBIl6kKgHiXqQqAeJepBo/z38J/U0uAHlaBkBl9I4GwAAAABJRU5ErkJggg==' because it violates the following Content Security Policy directive: "img-src 'self'".

This comes from pikaday.js which is the date picker we use.

Other than that this PR looks like its good and solves the issues we were having previously.

[pete-the-pete]

sure, i'll take a look this evening, sorry I missed it.

[jkleinsc]

Fixes #285

[jkleinsc]

Thanks for the PR @pete-the-pete !

[pete-the-pete]

My pleasure, should #285 be closed?

[jkleinsc]

@pete-the-pete yes, it should be closed. I thought I did close it, but it looks like I didn't