Adopt theming system of Angular Material

The SASS has been simplified so that different themes can be applied by
only using the $mdThemingProvider serivce.

The resulting design is more "Materialized" and less prone to the
future changes of Angular Material.

UI/WebServerResources/scss/core/base_styles/_base_style.scss

@@ -1,10 +1,5 @@
 /// _base_style.scss -*- Mode: scss; indent-tabs-mode: nil; basic-offset: 2 -*-
 
-
-main {
-  background-color: $background-base-color;
-}
-
 // Utility class to add padding on containers
 // Because of the border-box sizing model, padding can affect width specialy
 // in nested containers

UI/WebServerResources/scss/core/variables.scss

@@ -18,10 +18,10 @@ $version: '3.0.0';
 //@import '../themes/color-palette'; // fixme : clarify if it is needed or assure by javascript
 @import 'components/palette';        // fixme : The maps in color-palettes are more js then scss
 
-$primary-color:            sg-color($sogoBlue, 300) !default;
+//$primary-color:            sg-color($sogoBlue, 300) !default;
 //$foreground-primary-color: rgba($foreground-base-color, 0.73) !default;
-$foreground-primary-color: rgba($primary-color, 0.87);//override
-$background-base-color:    sg-color($sogoPaper, 200);
+//$foreground-primary-color: rgba($primary-color, 0.87);//override
+//$background-base-color:    sg-color($sogoPaper, 200);
 
 // Typography
 // ------------------------------