Changes for Saved Links widget styles on home and interior pages

[benlk]

This is what we're trying to match, from #51 and #48:

This isn't entirely possible, for the following reasons:

• That light serif is not included in the fonts available on the site
• The Saved Links widget doesn't capture favicons (https://github.com/INN/link-roundups/issues/19)

So this is what we've got:

• On posts:
• On homepage:

[benlk]

Updates from client review, written by @MirandaEcho in #52:

For sidebar content: Just the links and the newsletter. Links at the top, signup box, and then the newsletter roundup.

Also, to make sure we're on the same page, the existing boxes for the email digests need to be redesigned; we have a suggestion in the mockup. The existing boxes are confusing and use up too much real estate.

So:

• [x] reorder Main Sidebar: saved links, ENN newsletter signup widget, the Link Roundups widgets
• [x] make the title of the ENN newsletter signup widget editable
• [x] adjust styles on ENN Newsletter signup widget: smaller title aligned left and serif, checkboxes in vertical column, left-aligned subscribe button
• [x] tie the fancy Link Roundups widget styles to the .default widget-background class
• [x] create alternate styles for .reverse that match the mockup in https://github.com/INN/umbrella-energynewsnetwork/issues/51: small headlines, light grey background, no breaks between widgets,

[benlk]

By the power of CSS, these 6 widgets have become one!

[benlk]

Now includes code changes from https://github.com/INN/umbrella-energynewsnetwork/issues/57.