Merge: Nitdoc: some fixes and cleaning

* Fixes the topmenu brand display
* Update bootstrap version to v3.3.4
* Avoid nesting of DefinitionArticle to facilitate tabular display (next PR)

Demos are ready: [stdlib](http://gresil.org/jenkins/job/CI-nitdoc/ws/doc/stdlib/index.html) [nitc](http://gresil.org/jenkins/job/CI-nitdoc/ws/doc/nitc/index.html)

Pull-Request: #1314
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>