Normalize head date (server: Date, client: string)

[MoOx]

Following #395

gray-matter transform date field to Date. But on client side, we have raw json, so string. We should normalize that somewhere. Maybe after gray-matter call.

[thangngoc89]

Looks like this is a YAML feature see https://github.com/nodeca/js-yaml#supported-yaml-types.

[MoOx]

So maybe we should normalize in the emitted collection on the client side.

[thangngoc89]

I think normalize everything to string is better. Less code on client size. And less magic. I don't want user to ask us about what's going on

[thangngoc89]

Using JSON.parse and JSON.stringify should be the easiest (and probably fastest) way to fix this. But this might impact the loader's performance. Will open another issue about this.

[MoOx]

FYI yahoo/serialize-javascript#16

I successfully used my PR but this works for collection only: pages are JSON. I AM SO FUCKIN STUPID.

Blocked by #434 for a full resolution, meanwhile I will force dates to be ISOString on node, but JS with dates is kind of ready.

[bloodyowl]

Going to be fixed with #925

[MoOx]

What is your plan for this?

[bloodyowl]

everything as a string, and we dont care about the format as long as it's parsable by Date in order to sort posts

[MoOx]

Not a problem with v1