Add the "Vertical service bar" preference.

This controls whether the service bar shows up horizontally on the top
or vertically on the left.

app/view/preferences/Preferences.js

@@ -146,6 +146,12 @@ Ext.define('Rambox.view.preferences.Preferences',{
 						,value: config.hide_menu_bar
 						,hidden: process.platform === 'darwin'
 					}
+					,{
+						 xtype: 'checkbox'
+						,name: 'left_tabbar'
+						,boxLabel: 'Vertical service bar'
+						,value: config.left_tabbar
+					}
 					,{
 						 xtype: 'combo'
 						,name: 'default_service'

electron/main.js

@@ -20,6 +20,7 @@ const config = new Config({
 	 defaults: {
 		 always_on_top: false
 		,hide_menu_bar: false
+		,left_tabbar: false
 		,window_display_behavior: 'taskbar_tray'
 		,auto_launch: !isDev
 		,flash_frame: true