CologneBlue rewrite: rework otherLanguages(), CSS: serif font

CologneBlue rewrite: rework otherLanguages(), CSS: serif font

We have to override SkinTemplate->formatLanguageName() in SkinCologneBlue
not to capitalize the language names, as they are not actually used in the
sidebar and look better this way.

This change revealed that CologneBlue does not set the base font for the
page, causing text marked as being in a different language (e.g., language
links) to be displayed in a different fond in some browsers. Adding
"font-family: serif" to body fixed the issue.

Change-Id: I8b56ccb6f9a2ba47613f135754b5a133a6870412