Extract SSL verify none warning to its own method (#837)

A tiny refactor where we extract the warning you get when setting SSL
verify mode to `VERIFY_NONE` into its own method. No real impetus for
this except that it extracts very nicely, and that gets us to a smaller
`create_connection` method.

lib/stripe/connection_manager.rb

@@ -109,14 +109,7 @@ def execute_request(method, uri, body: nil, headers: nil, query: nil)
         connection.cert_store = Stripe.ca_store
       else
         connection.verify_mode = OpenSSL::SSL::VERIFY_NONE
-
-        unless @verify_ssl_warned
-          @verify_ssl_warned = true
-          warn("WARNING: Running without SSL cert verification. " \
-            "You should never do this in production. " \
-            "Execute `Stripe.verify_ssl_certs = true` to enable " \
-            "verification.")
-        end
+        warn_ssl_verify_none
       end
 
       connection
@@ -134,5 +127,15 @@ def execute_request(method, uri, body: nil, headers: nil, query: nil)
         [u.host, u.port, u.user, u.password]
       end
     end
+
+    private def warn_ssl_verify_none
+      return if @verify_ssl_warned
+
+      @verify_ssl_warned = true
+      warn("WARNING: Running without SSL cert verification. " \
+        "You should never do this in production. " \
+        "Execute `Stripe.verify_ssl_certs = true` to enable " \
+        "verification.")
+    end
   end
 end