Update comrak

This gets rid of one of our 4 versions of `quote`.

Author: jyn514

Cargo.lock

@@ -24,7 +24,7 @@ url = "1.4"
 libc = "0.2"
 badge = { version = "0", path = "src/web/badge" }
 failure = "0.1.3"
-comrak = { version = "0.5", default-features = false }
+comrak = { version = "0.7", default-features = false }
 toml = "0.5"
 html5ever = "0.24"
 schemamama = "0.3"