Update to WC 2.6.4

[spencerfinnell]

Check template files, hooks, etc.

[adampickering]

Please read over the support topics posted here https://wordpress.org/support/plugin/woocommerce-simple-registration to see if we can improve this plugin for users, I believe we just need to update the plugin files to the latest WC version

[turtlepod]

I updated the plugin with new WC form + password meter now working.
https://github.com/Astoundify/woocommerce-simple-registration/tree/david
please check first, and pull/merge :)

[adampickering]

great i'll check this out today and if all is good, i'll merge and upload to wp.org