Revert "Work around issues with old IE."

This reverts commit e6df569ad0d6212717a2221f0b8a6784c364f3e8.

Conflicts:
	index.html
Revert "Remove selectivizr-min.js."

This reverts commit b6728c75021002615502516a1df97fd1a3552d63.
Downgrade selectivizr; now it works again for IE 7-8.