Rewriting to follow Zen Cart Standards

-moving missing_images.php to admin folder
-removeing (IMHO) the overcomplicated database connection, ZC already
facilitates in this.
-Moving defines to language file
-moving css to seperate file
-added standard zc admin page layout
Merge pull request #1 from Zen4All/master

This coding will start the basis of Missing Images for ZenCart 2.0.