[OpenAPI.next] validate (not lint) versions/3.*.md with mdv

[MikeRalphson]

Checks for broken links and images with missing alt tags and fenced code-blocks with no defined language.

This change also updates the Node.js version used on Travis from 0.10.36 (which is now unsupported) to a LTS version (6.x)

Issues identified have been fixed.

[webron]

I don't know how, but it looks like a bunch of things got messed up when you look at the rendered view.
For example:

• https://github.com/MikeRalphson/OpenAPI-Specification/blob/11af30e39d1319d2d55828333cedcaec7f3f6dd4/versions/3.0.md#fixed-fields-13
• https://github.com/MikeRalphson/OpenAPI-Specification/blob/11af30e39d1319d2d55828333cedcaec7f3f6dd4/versions/3.0.md#patterned-fields-4

[webron]

Can the check to add ```text be configured and removed? It's not really needed and just adds noise.

[MikeRalphson]

@webron thanks for the heads-up. The raw diff looked ok. Will rework,

[MikeRalphson]

@webron commits reworked but table-formatting issues still remain.

My theory is that GitHub have recently changed their markdown renderer and the <span>&#124;</span> hack in table cells no-longer works.

You can see the same problem in an unrelated PR by @willdady here.

The following markdown

Column A|Column B|Column C|Overflow
---|---|---|---
Cell A|Cell <span>&#124;</span>B|Cell C

renders as:

Column A	Column B	Column C	Overflow
Cell A	Cell |B	Cell C

One option is to use another Unicode bar character:

Column A	Column B	Column C	Overflow
Cell A	Cell ¦B	Cell C

Or escaping as per the GFM spec:

Column A	Column B	Column C	Overflow
Cell A	Cell |B	Cell C

I suspect the 'published' versions/3.0.md at RC0 is showing cached html from before the change.

[webron]

Thanks. I'll look into it.

[webron]

@MikeRalphson - I should have merged the PRs in a different order, but alas... I'm trying to manually resolve issues for some PRs but would you mind resolving these yourself?

[webron]

@MikeRalphson I see you're pushing changes, lmk when done.

[MikeRalphson]

@webron those four conflicts (between fixed links and fixed table formatting) are resolved.