Markdown: decode single quotes in fenced code blocks

Props @synapticism
See #403
Infinite Scroll: remove ternary with is_ssl

home_url() is already aware of the scheme
https://core.trac.wordpress.org/browser/tags/3.8.1/src/wp-includes/link-template.php#L1952
Carousel: remove ternary with is_ssl

admin_url is already aware of the scheme
https://core.trac.wordpress.org/browser/tags/3.8.1/src/wp-includes/link-template.php#L2065
Use set_url_scheme instead of is_ssl
JSON API: use set_url_scheme instead of is_ssl
Comments: use set_url_scheme instead of is_ssl
Minileven: remove protocol from Google Font URL

wp_register_style accepts protocol-agnostic URLs
http://codex.wordpress.org/Function_Reference/wp_register_style#Parameters
Notifications: use set_url_scheme instead of is_ssl
Audio shortcode: use set_url_scheme instead of is_ssl
Youtube Shortcode: use set_url_scheme instead of is_ssl
Stats: use set_url_scheme instead of is_ssl
Subscriptions: use set_url_scheme instead of is_ssl
Facebook Likebox widget: use set_url_scheme instead of is_ssl
Top Posts Widget: use set_url_scheme instead of is_ssl
Stats: remove extra semi-colon
Merge pull request #404 from jeherve/403-github

Markdown: decode single quotes in fenced code blocks
Update youtube.php

Allows 1080p and 720p playbacks on embeds.
Update youtube.php

Because of the YouTube term requires either "hd720" or "hd1080" did I end up cutting the code down to the original tag.
Update youtube.php

Just forgot to remove the old code. Here you go.
Youtube: Updates variable names. Merges and closes #245