Include more HTML error checks

[William Entriken]

See

https://github.com/gjtorikian/html-proofer#configuring-html-validation-rules

@Raza403

[William Entriken]

Here is the documentation example:

opts = { :check_html => true, :validation => { :report_script_embeds => true } }

And here is where we need to make changes: https://github.com/fulldecent/lightning-sites/blob/master/lib/lightning_sites.rb#L244

[William Entriken]

Thank you @Raza403, this is fixed and published

[William Entriken]

Work here is incomplete.

Evidence:

https://travis-ci.com/Raza403/test/builds/151384593

Recommendation: