Add raw and rendered to schema

[websupporter]

Solves #2670

For usual posts we give the title, the excerpt, the guid and the content in two formats: raw and rendered. In case of revisions, we just gave the raw content. This PR extends the schema, which acts now like we know it from usual posts.

So, instead of content being a string it would now be an object:

content : {
     raw : "",
     rendered: "",
}

The raw property would only be send when context is set to edit.

[codecov-io]

Current coverage is 94.54% (diff: 97.67%)

Merging #2693 into develop will increase coverage by 0.01%

@@            develop      #2693   diff @@
==========================================
  Files            11         11          
  Lines          3617       3627    +10   
  Methods         172        173     +1   
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits           3419       3429    +10   
  Misses          198        198          
  Partials          0          0          

Powered by Codecov. Last update bb69048...a7525c5

[websupporter]

I'll check the password protected. Not quite sure if its really needed. If its needed, the code is missing the function.

[websupporter]

I've made some tests. When I have a password protected post, the password is not written in the database for the revisions. I've removed the password checks.

[BE-Webdesign]

Looks good to me! Going to do one last look through, I am not sure the consensus on whether to add this feature but +1 from me. It makes for better potential authoring experiences.

[websupporter]

While I was working on it I was thinking of a small slider for loggedin authors in the front end where they would be able to slide back in history and see their revisions rendered in the frontend. Small toy, but hey. Wouldn't work without the rendered properties.

[kadamwhite]

👍 from @rmccue, myself & @BE-Webdesign. There is an open question voiced by Ryan around whether this change moves Revisions sufficiently close to Posts that they should just extend the posts controller. That will be addressed in a separate issue.