Make footer stick to the bottom of the page
- Use JavaScript to determine height of `.page_footer` to apply padding to `body` avoiding any content overlap
- Absolute position `.page_footer` to bottom of the page

Set default `lang` to `en`

Merge branch 'hotfix/3.3.2' into develop

Update CHANGELOG and bump version to 3.3.2
- Close #396

Updated main.min.js

Fixed condition that should be notted.

Fixed overlay when 'author__urls-wrapper button' is not present.

Merge branch 'release/3.3.1' into develop

Merge branch 'release/3.3.1'

Update CHANGELOG and bump version to 3.3.1

Improve link posts in archive listings
- Remove `target="_blank"` anti-pattern
- If link post point title to source article
- Switch star icon to a link to indicate "permalink" and markup semantically with `rel="permalink"`
- Reduce opacity of permalink icon
- Adjust hover styles due to shuffling around <a> element
- Close #276

Indicate the relationship between component URLs in a paginated series
- Apply rel="prev" and rel="next" to pages that use site.paginator
- Ref ~> https://webmasters.googleblog.com/2011/09/pagination-with-relnext-and-relprev.html
- Close #253

Enable image popup on < 500px wide screens
- Close #385

Update gems
- Update github-pages (86), ffi 1.9.13, jekyll-mentions 1.1.3, and rouge 1.11.1

Merge branch 'release/3.2.13' into develop

Merge branch 'release/3.2.13'

Update CHANGELOG and bump version to 3.2.13

Merge branch 'feature/data-files' into develop

Default locale to `en`

Change navigation links to sample data