Added inital credits markdown

Author: Michael Skelton

CREDITS.md

@@ -0,0 +1,4 @@
+# September 2017
+The original class for this project was taken from [Reconnoitre](https://github.com/codingo/Reconnoitre) which adapted virtual host discovery code from [teknogeek's virtual-host-scan](https://github.com/teknogeek/virtual-host-discovery-py).
+
+This in turn was adapted from [jobertabma's virtual-host-discovery](https://github.com/jobertabma/virtual-host-discovery).

lib/core/virtual_host_scanner.py

@@ -98,4 +98,6 @@ def likely_matches(self):
         d=df.groupby("val_col").filter(lambda x: len(x) <= self.unique_depth)
         matches=((d["key_col"].values).tolist())
 
-        return matches
+        return matches
+
+    def page_difference_ratios