JBIDE-17950 - Improve rendering on mobile and tablets

Mainly changing the rendering of the home page when displayed on mobile and tablets:
- using a different banner (http://static.jboss.org/jbosstools/images/tools-banner-1180px.png -> http://static.jboss.org/jbosstools/images/tools_200x150.png)
- hidding the screenshot on the 'hero-unit' and reducing the font size and changing the text alignment

(big diff is probably due to changes in autocrlf in my git config :-/ )