Clean up and organize css properly.
Improve padding on #home page

Been bugging me for some time...
Upgrade angular libs
Merge pull request #1435 from hypothesis/tags-redux

Tag Styles
Add markdown preview, add markdown help icon, and adjust styles for markdown output.
Rename icon-markdown in icomoon.css
Kill placeholder, reposition markdown icon, clean up code.
Hide comment icon when editing.
Cleaned up markdown stylings.
Added fonts.
Add onhover red to links in nav tabs.
Kill .tag-preview and add more stylings for code element.
Fixed regression where annotations weren't collapsing correctly.
Fix some problems identified by @aron.
Move css related to annotation cards to annotations.scss file.
Use tabbable directive for preview
Whitespace
Merge pull request #1418 from hypothesis/markdown

Add markdown preview, add markdown help icon, and adjust styles for markdown output
Restore the markdown icon that I broke

This isn't the most elegant thing. It may be time to drop
angular-bootstrap. Ah, well.
Reduce tag list margin back to match other padding