Land rapid7#3775 - ssh_login_pubkey fix for the uninit prepended_creds bug

Closes rapid7#3774

Author: wchen-r7

modules/auxiliary/scanner/ssh/ssh_login_pubkey.rb

@@ -198,7 +198,7 @@ def run_host(ip)
 
     keys = prepend_db_keys(keys)
 
-    print_brute :level => :vstatus, :ip => ip, :msg => "Testing #{keys.key_data.count} keys"
+    print_brute :level => :vstatus, :ip => ip, :msg => "Testing #{keys.key_data.count} keys from #{datastore['KEY_PATH']}"
     scanner = Metasploit::Framework::LoginScanner::SSH.new(
       host: ip,
       port: rport,
@@ -240,12 +240,10 @@ def run_host(ip)
 
   class KeyCollection < Metasploit::Framework::CredentialCollection
     attr_accessor :key_data
+    attr_accessor :key_path
 
     def initialize(opts={})
-      @username = opts[:username]
-      @user_file = opts[:user_file]
-      @key_path = opts.fetch(:key_path)
-
+      super
       valid!
     end