Add Tag plugin link for 'Jekyll Twitter Plugin'; A Liquid tag plugin that renders Tweets from Twitter API.
allow Enumerables to be used with "where" filter

Enumerable module responds to `select` so this shouldn't be a problem here. Typical use case would be an object from a plugin being passed through a where filter.
site_template/_includes/head.html: Minor refactoring.

Remove unneeded end tag, and also strip newlines.
Move `X-UA-Compatible` just after `meta charset`.
site_template/feed.xml: Remove unneeded space.
Update normalize.css to v3.0.2.
Merge pull request #2979 from rob-murray/add-twitter-tag-plugin
Update history to reflect merge of #2979 [ci skip]
Update continuous-integration.md

Fix minor typo
Fix site:update_normalize_css so it works with new integrated Sass workflow. [ci skip]

Ref: #2981
Merge pull request #2981 from XhmikosR/normalize
Update history to reflect merge of #2981 [ci skip]
Merge pull request #2984 from kevgathuku/patch-1
Update history to reflect merge of #2984 [ci skip]
Merge pull request #2980 from tamagokun/patch-1
Update history to reflect merge of #2980 [ci skip]
Revert "Allow Enumerables to be used with "where" filter"
Merge pull request #2985 from jekyll/revert-2980-patch-1

Revert "Allow Enumerables to be used with "where" filter"
Remove reverted #2980 from History.
Merge pull request #2982 from XhmikosR/page-description
Update history to reflect merge of #2982 [ci skip]