Merge branch 'release/4.0.4'

Conflicts:
	README.md

Merge branch 'feature/theme-gem' into develop

Remove `prepend: "/"` from includes and add to image path's instead

Make author avatar optional

Replace base_path with `absolute_url` filter where possible

Don't prepend `author.avatar` paths with `/` when path contains `://`

Allow images to be placed in other folders
- Remove `images/` only restriction and encourage placement in `assets/images/` instead

Merge branch 'release/3.4.8'

Fixed Last.fm URL (#540)

lastfm.com/user... results in a server error, last.fm/user... is the correct URL.

Merge branch 'release/3.4.5'

get Follow-Button label from ui-text and default to "Follow" (#496)

Merge branch 'release/3.3.5'

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

Merge branch 'release/3.2.12'

Merge branch 'feature/author-override-check' into develop

Merge branch 'author-profile-update' of https://github.com/ZenHarbinger/minimal-mistakes into feature/author-override-check

Updated author-profile.html in the event that there is no authors.yml file.

Merge branch 'release/3.2.3'

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

Merge branch 'release/3.1.5'