Merge branch 'release/3.4.3'

Use page.header.teaser instead of site.og_image in twitter:image and og:image meta tags (#466)

Merge branch 'develop' of https://github.com/mmistakes/minimal-mistakes into develop

* 'develop' of https://github.com/mmistakes/minimal-mistakes:
  formats og:locale tag with underscores (#465)

formats og:locale tag with underscores (#465)

See http://fbdevwiki.com/wiki/Locales

Merge branch 'release/3.3.5'

Add `en` default text to `site.locale` strings
- Close #407

Merge branch 'release/3.3.1'

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

Merge branch 'release/3.2.9'

Merge branch 'feature/og-overlay-image' into develop

Merge branch 'master' of https://github.com/jhabdas/minimal-mistakes into feature/og-overlay-image

Use header overlay images for Open Graph image

Merge branch 'release/3.2.7'

Merge branch 'feature/yandex-alexa-patch' into develop

Merge branch 'patch-1' of https://github.com/jhabdas/minimal-mistakes into feature/yandex-alexa-patch

Fix branch logic for Yandex and Alexa. Closes #347

Merge branch 'release/3.2.3'

Replace contains "http" with contains "://"

Merge branch 'release/3.1.3'

Fix SEO author bug
- If `twitter.username` is set and `author.twitter` is nil bad things happen.
- Close #289