Enhance layout

...pp/src/main/java/edu/kit/scc/webreg/bean/HeadBarBean.java

...sources/META-INF/resources/primefaces-kit-theme/theme.css

bwreg-webapp/src/main/resources/msg/messages_de.properties

bwreg-webapp/src/main/resources/msg/messages_en.properties

bwreg-webapp/src/main/resources/msg/messages_fr.properties

bwreg-webapp/src/main/webapp/resources/css/std-ext.css

bwreg-webapp/src/main/webapp/resources/css/std.css

bwreg-webapp/src/main/webapp/service/set-sshkey.xhtml

bwreg-webapp/src/main/webapp/template/head-bar.xhtml

bwreg-webapp/src/main/webapp/user/index.xhtml

bwreg-webapp/src/main/webapp/user/register-service.xhtml

bwreg-webapp/src/main/webapp/welcome/index.xhtml

.../java/edu/kit/scc/webreg/bootstrap/ApplicationConfig.java