add missing 'as'
Register subclasses of subclasses of Jekyll::Plugin

The Sass and SCSS converters are practically the same – only different in
the input syntax and file extension. As such, we've created
`Jekyll::Converters::Scss` which is a subclass of `Jekyll::Converter`, and
`Jekyll::Converters::Sass` which is a subclass of
`Jekyll::Converters::Scss`. When `Site#instantiate_classes` is called on
`Jekyll::Converter`, it only instantiates the `Scss` converter, not the
`Sass` converter. This change fixes that.

Fixes #2334.
Update history to reflect fixing of #2334.
Merge pull request #2337 from sankage/grammar-slam
Update history to reflect merge of #2337 [ci skip]
Update site history.
Use site.title instead of site.name in site template

Fixes #2324.
Update history to reflect the closing of #2324.
Require mercenary v0.3.3 or greater (below v0.4.0)
If the input is a string but Time.parse can't parse it, maybe it's a UNIX timestamp.

Fixes #2339
Update history to reflect the closing of #2339.
Fix baseurl default in the docs

Display the new baseurl default (commit: [97e9fb2](https://github.com/jekyll/jekyll/commit/97e9fb29b09fcd67f960000bea3af88f8d5bfab2)) in the docs.
Use kramdown.
Pure JavaScript for adding anchors.
Add font-awesome & Ben's CSS
Use HTML and CSS we just created.
Add font-awesome web fonts.
Merge pull request #2341 from albertogg/fix-baseurl-default-in-docs
Update history to reflect merge of #2341 [ci skip]
Add newlines, duh.