Write Glyphicons to _data, generate Glyphicons markup

This generates a glyphicons.yml file from the glyphicons.less source,
and then components.html uses that data to generate the Glyphicons docs
by iterating through the data. The _data directory was introduced in
Jekyll 1.3.0, and GitHub Pages is already on [version 1.4.2][1].

Fixes #11862.

[1] https://github.com/github/pages-gem/blob/master/github-pages.gemspec#L16
2 instead of 4 spaces in .csscomb.json
No leading pluses
Merge pull request #11939 from ZDroid/weird-indents

2 instead of 4 spaces in .csscomb.json
Merge pull request #11941 from ZDroid/left-plus

No leading pluses
Merge pull request #11930 from ssorallen/master

Write Glyphicons to _data, generate Glyphicons markup
Minor grammar change

'as well' was used twice in sentence
Merge pull request #11951 from bnewcomb/master

Fix sentence grammar
correct jsbin link
Fixes #11952: Refactor blockquote styles

* Deprecate .pull-right class for .blockquote-reverse
* Move font-size change to the parent, blockquote, instead of setting on the p element to allow more flexible content