Add forgottend square brackets

Fixed broken code that was missing square brackets and would break on machines
with no battery.

power_widget.lua

@@ -125,7 +125,7 @@ function widget:init()
   end
   self.device = get_data(
     devices[DeviceType.Battery]
-      or devices[DeviceType"Line Power"])
+      or devices[DeviceType["Line Power"]])
 
   self.tooltip = awful.tooltip({ objects = { widget },})
   self.gui_client = ""

rockspec/power_widget-0.3.1-1.rockspec

@@ -0,0 +1,27 @@
+package = "power_widget"
+version = "0.3.1-1"
+source = {
+   url = "git://github.com/stefano-m/awesome-power_widget",
+   tag = "v0.3.1"
+}
+description = {
+   summary = "A Power widget for the Awesome Window Manager",
+   detailed = [[
+    Monitor your power devices in Awesome with UPower and DBus.
+    ]],
+   homepage = "https://github.com/stefano-m/awesome-power_widget",
+   license = "GPL v3"
+}
+supported_platforms = {
+   "linux"
+}
+dependencies = {
+   "lua >= 5.1",
+   "upower_dbus >= 0.3.0, < 0.4"
+}
+build = {
+   type = "builtin",
+   modules = {
+      power_widget = "power_widget.lua"
+   }
+}