define base theme : add palette definitions to module initialization

UI/WebServerResources/scss/components/bottombar/_extends.scss

@@ -7,10 +7,10 @@
 /// botttombar extends
 ///
 
-.sg-bottombar {
+md-toolbar.sg-bottombar { // overclafied to compensate for the injected css
   @extends md-toolbar;
 
-  background-color:#212121; // fixme : use a variable
+  background-color:$bottombar-color;
   position: fixed;
   bottom: 0px;
   left: 0px;

UI/WebServerResources/scss/components/bottombar/bottombar-theme.scss

@@ -1,5 +1,5 @@
-md-toolbar.md-THEME_NAME-theme {
-  background-color: '{{primary-color}}';
+sg-bottombar.md-THEME_NAME-theme {
+  background-color: $bottombar-color;
   color: '{{primary-contrast}}';
 
   .md-button {

UI/WebServerResources/scss/components/bottombar/bottombar.scss

@@ -11,4 +11,5 @@
 @import 'components/toolbar/toolbar.scss';  // todo : remove when settings are done
 @import "mixins";
 @import "extends";
+@import "bottombar-theme";
 // -----------------------------------------