First set of UI improvements

[kylecourounis]

Here are some of the UI changes:

• Improved the position of the header/title text on the dashboard pages.
• Improved the sidebar
• Improved the AI drawer
• Greatly improved the way new documents are created
• Improved the editor UI to give more space to write by default and make it less claustrophobic overall.

Things we still need to do:

• Font continuity - aside from the homepages, I got rid of all the different fonts (Helvetica, Verdana, Arial, etc), on most of the CSS elements and just let it use the system font. We still need to pick a solid font and apply it across the site, but this is a start to making that easier.
• Tags are still kind of broken and need work - you can add them, but you can't see them anywhere in the document. Still trying to add them to the modal popup.
• Improve the Friends page. I'm not liking the way the request box sits on the top of it.

[briangormanly]

Looks good.