Creation of a Version Banner for /v/, with cookie based 'Don't show again'.
Replaced {{ site.url }}s with absolutes.
tidy graphics of version selection
fix javascript for cookies, and extend it to allow turning on/off all warnings (clear cookie or set master cookie)
Merge remote-tracking branch 'jdtoy/version-warning' into version-warning

Conflicts:
	docs/_layouts/page.html -- both fixed links, i modified text too
Merge pull request #1 from ahgittin/version-warning

tweak text and colours, add links for enabling/disabling warnings
Changes to warning wording, clear_user_versions() uses removeCookie() method.
Couple of small css tweaks to warning banner.
Added thumbnail warning banner to /meta/versions.html
Minor JS formatting.
Overtweaked. Restoring (?) $('#page_notes').fadeIn('slow');
Removed banner thumbnail from /meta/versions. Removed unnecessary window.location.reload()s
Merge pull request #604 from jdtoy/version-warning

Docs: Version Banner for /v/<version>