Add luarocks loader to rc.lua

rc.lua

@@ -1,3 +1,6 @@
+-- If LuaRocks is installed, make sure that packages installed through it are
+-- found (e.g. lgi). If LuaRocks is not installed, do nothing.
+pcall(require, "luarocks.loader")
 -- libraries {{{
 local awful = require("awful")
               require("awful.autofocus")
@@ -5,6 +8,7 @@ beautiful   = require("beautiful")
 naughty     = require("naughty")
 conf        = require("localconf")
               require("errors")
+gears       = require("gears")
 inspect = require("lib.inspect")
 wibox = require("wibox")
 -- }}}