Updated the cleaner module to give the clean_paper_trail_versions method the option of passing in a value. Also created a keep versions method that keeps the specified number of versions.

lib/paper_trail/cleaner.rb

@@ -13,7 +13,7 @@ module PaperTrail
     end
 
     def sanitize(group)
-      group.pop
+      group = keep_versions(group)
       if group.size > 0
         group.each do |member| 
           member.destroy
@@ -21,6 +21,13 @@ module PaperTrail
       end
     end
 
+    def keep_versions(group)
+      @keeping_versions.times do
+        group.pop
+      end
+      group
+    end
+
     def analyze_grouping(grouping)
       grouping.each_value do |group|
         sanitize(group)
@@ -39,7 +46,8 @@ module PaperTrail
       end
     end 
 
-    def clean_paper_trail_versions
+    def clean_paper_trail_versions(keeping = 1)
+      @keeping_versions = keeping
       acquire_version_info
       examine_and_clean_versions
     end