added some keyboard shortcuts to README and lots of cleanup

layout/top-bar.lua

@@ -45,7 +45,6 @@ local TopBar = function(s, offset)
     -- SYSTEM DETAILS
     -- ==============
     local volume_widget = require('widget.volume')
-    local battery_widget = require('widget.battery')
     local clock_widget = require('widget.clock')
     local mem_widget = require('widget.memory')
     local cpu_widget = require('widget.cpu')
@@ -54,8 +53,6 @@ local TopBar = function(s, offset)
     local system_details = wibox.widget {
             systray,
             separator,
-            --battery_widget,
-            --separator,
             wibox.widget{
                 wibox.widget{
                     text = 'mem',