lock: use xss-lock instead of xautolock

xss-lock features nice integration with standard X screensaver
feature which makes it easy to trigger it or to disable it. Moreover, it
also has some logind integration to lock screen before suspend.

rc/xlock.lua

@@ -1,15 +1,7 @@
 -- Lockscreen
 
-local icons = loadrc("icons", "vbe/icons")
-
-xrun("xautolock",
-     awful.util.getdir("config") ..
-        "/bin/xautolock " ..
-        icons.lookup({name = "system-lock-screen", type = "actions" }))
-
 local lock = function()
-   awful.util.spawn(awful.util.getdir("config") ..
-                    "/bin/locker", false)
+   os.execute("xset s activate")
 end
 
 config.keys.global = awful.util.table.join(
@@ -17,5 +9,6 @@ config.keys.global = awful.util.table.join(
    awful.key({}, "XF86ScreenSaver", lock),
    awful.key({ modkey, }, "Delete", lock))
 
--- Configure DPMS
-os.execute("xset dpms 360 720 1200")
+-- Configure xss-lock
+os.execute(awful.util.spawn(awful.util.getdir("config") ..
+                            "/bin/xss-lock start"))