Follow naming convention for Lua

second-pass.lua

@@ -1,4 +1,4 @@
-function file_exists(name)
+function fileExists(name)
     local f=io.open(name,"r")
     if f~=nil then io.close(f) return true else return false end
  end
@@ -13,7 +13,7 @@ end
 return {
     {
       Meta = function(meta)
-        if file_exists("output.pdf") then
+        if fileExists("output.pdf") then
             meta["wordcount"] = countWords()
             meta["secondpass"] = true
         end