initial logging for LE registration

part of #94

lib/postal/lets_encrypt.rb

@@ -17,7 +17,14 @@ module Postal
 
     def self.register_private_key(email_address)
       registration = client.register(:contact => "mailto:#{email_address}")
+      logger.info "Successfully registered private key with address #{email_address}"
       registration.agree_terms
+      logger.info "Terms have been accepted"
+      true
+    end
+
+    def self.logger
+      Postal.logger_for(:lets_encrypt)
     end
 
   end