Remove jQuery, use flatpickr instead of pikaday

[RobbieTheWagner]

ember-pikaday was using jQuery internally, so we had to move away from it. I chose flatpickr, but we could use anything else. I'm having trouble getting the tests to pass currently.

Resolves #590

[RobbieTheWagner]

@teddyzeenny the one test failure I am getting here is related to https://github.com/emberjs/ember-inspector/blob/master/tests/acceptance/object-inspector-test.js#L564.

not ok 37 Chrome 67.0 - Object Inspector: Date fields are editable
    ---
        actual: >
            view:getTree
        expected: >
            objectInspector:saveProperty
        stack: >

It seems objectInspector:saveProperty is not being called, although it does seem to save the new dates when I manually click through it. I was thinking maybe fillIn does not trigger the same things on flatpickr as it did on pikaday. Any ideas?

[nummi]

Have you tried calling other events manually? I see a keydown — what about keyup or blur?

[RobbieTheWagner]

@nummi I fixed that, everything works, I just need someone to review the PR.

[Bestra]

I'll review

[Bestra]

I tried this locally and it looks like flatpickr is functioning as intended. I loaded up http://ember-flatpickr.shipshape.io/ and was able to inspect the dates on the date picker component using it. Hitting 'esc' closed the picker as expected. 👍