adding support for web.archive.org

[kishore881]

PR for Issue #19

• new fixer for web.archive.org
• updated css for select tag in popup to use "initial" color. the color style for select tag on web.archive.org is applied to the popup as well and the text is being rendered in white on white background. Hence the css change
• started passing label as well from the Fixer along with url. used "snapshot" as label for the web.archive.org link and renamed related vars to be agnostic of post/snapshot

Demo:

web-archive.mov

[msramalho]

Thanks for this great addition! The new HoverPopup is more informative now and I used the suggestion to drop all #!