Add branding to site

This adds the logo to the website in a RWD-way. Also the design of the
nav and branding on the home page is different from the content pages.

This also fixes issues with the content in the footer fitting on small
screen devices.
Update home page to align nav menu above logo
Merge pull request #75 from ericf/branding

Add branding to site
Tweak content and display on Home page

This also add a section about browser and Node.js support.
Merge pull request #77 from ericf/homepage-tweaks

Tweak content and display on Home page
Update intl-* deps and rename to dust-intl
Fix Dust page to use proper `registerWith`
Merge pull request #78 from ericf/dust-intl

Update intl-* deps and rename to dust-intl
Add Intl RelativeFormat to GitHub page
Merge pull request #79 from ericf/github-repos

Add Intl RelativeFormat to GitHub page
No need to escape HTML in Guide
Merge pull request #80 from okuryu/unescape-html

No need to escape HTML in Guide
Refactor LocaleSelect to work with valueLink

This makes the LocaleSelect React component work in situations where
the React ValueLink add-on is used.
Rename Code component to CodeBlock
Add more React propTypes validation
Improve rendering of examples using tab view

This adds a tabbed interface to the various source code snippets that
go into making up an example. Overall these visual changes make it
easier to view an example's source and output as a whole unit.
Update Express so Accept-Language negotiation works
Merge pull request #82 from ericf/accept-language

Update Express so Accept-Language negotiation works
Merge pull request #81 from ericf/example-rendering

Improve rendering of examples and composition of React components