Several big visual regressions in installer

Problem/Motivation

The installer got really broken looking recently. While it does work, it reminds me of the old PHPNuke days where even the page encoding was not right. This is sad.

Some errors I noticed:

1. The page encoding is not specified, autodetected as Latin-1 so all foreign languages with characters not in Latin-1 are broke.
2. The font size was increased, which makes the page title really odd, looks visually off and breaks the arrow design in the step bar.
3. The form widgets are different, the button is noticably uglier.

Note that I filed this as critical because its emberassing. You could not tell lots of the language names what they even are...

Proposed resolution

Fix the markup and styling.

Remaining tasks

Fix the markup and styling, review.

User interface changes

Installer fixed.

API changes

None.