Added the ability to enable borders for the bar. (#428)

* Added the ability to configure a border for the bar.

* Added the right color for configs

themes/gruvbox_vivid.json

@@ -341,5 +341,6 @@
   "theme.bar.menus.menu.network.switch.puck": "#504945",
   "theme.bar.menus.menu.network.switch.disabled": "#3c3836",
   "theme.bar.menus.menu.network.switch.enabled": "#b16286",
-  "theme.bar.buttons.systray.customIcon": "#ebdbb2"
+  "theme.bar.buttons.systray.customIcon": "#ebdbb2",
+  "theme.bar.border.color": "#83a598"
 }