Simplified, localized language switcher

Updated to use a langagues.html include with just the translation
links, instead of parsing config values. Added css declaration
for formatting.

Translations based on debian.org and wikipedia; should be verified
by native speakers.
Merge branch 'locale-switcher' of https://github.com/devdiva/www.ruby-lang.org into locale-switcher

Conflicts:
	_includes/languages.html