Use unified CSS files from site

[jpallen]

This goes with jpallen/site#c40071f, and is a proof of concept that lesson can
share the same CSS as site. I haven't looked at merging slideshow.css yet
though. This commit brings the CSS here up to date with the at site (if
c40071f is merged) although doesn't address how we'll keep these in sync in
future.

[jpallen]

The PR to get these CSS changes into site are in swcarpentry/DEPRECATED-site#751

[rgaiacs]

@jpallen Thanks for this pull request. Could you split this pull request in two? One with

• _includes/header.html
• _layouts/page.html
• css/badge.css
• css/bootstrap/img/glyphicons-halflings-white.png
• css/bootstrap/img/glyphicons-halflings.png
• css/lesson.css
• css/local-fonts/zhcz-_WihjSQC0oHJ9TCYBsxEYwM7FgeyaSgU71cLG0.woff
• css/swc-bootstrap.css
• css/swc-workshop-and-lesson.css
• css/swc.css

that needs to be merge into core and the another one with

• 01-one.html
• 02-two.html
• LICENSE.html
• discussion.html
• index.html
• instructors.html
• reference.html

that needs to be merged into gh-pages. Later we will merge core into gh-pages.

[jpallen]

Yes, I can split it up. Note that changing either the CSS or HTML without changing the other will leaving the styling broken. Is it ok to have each PR be a breaking change, so long as they work together?

[gvwilson]

I think so - I'm guessing Raniere wants it to be easier to cherry-pick
the CSS changes into another repo, but that's just a guess.

[jpallen]

@r-gaia-cs I've created the separate pull requests now.

[gvwilson]

@r-gaia-cs if this looks good to you, please merge. (We'll worry about copying the CSS into 'core' later.)

[rgaiacs]

I've created the separate pull requests now.

Thanks. I'm closing this issue since I will merge #141 and #142.