fix for custom content dir

lib/wpscan/wp_target.rb

@@ -44,7 +44,13 @@ class WpTarget < WebSite
     fail "The target is responding with a 403, this might be due to a WAF or a plugin.\n" \
           'You should try to supply a valid user-agent via the --user-agent option or use the --random-agent option' if response.code == 403
 
-    if response.body =~ /["'][^"']*\/wp-content\/[^"']*["']/i
+    if wp_content_dir
+      dir = wp_content_dir
+    else
+      dir = 'wp-content'
+    end
+
+    if response.body =~ /["'][^"']*\/#{Regexp.escape(dir)}\/[^"']*["']/i
       wordpress = true
     else