[No demo store] Enable the checkout user flow by default and add a checkbox for that feature

2. A checkbox that says : "Allow checkout for anonymous users."

at this moment the "access checkout" is enabled by default.
i could find 2 places where this is set:
- commerce_kickstart_install function in "commerce_kickstart.install" file
- in commerce_kickstart_user.features.user_permission.inc as user permission feature, this module is enabled by default no matter we have any option about demo content or other extras checked

the question is: where should we have implemented
as it is now, in both places or just one (an which)?

commit for 1. ( User flow for login and checkout process enabled by default) - https://code.drupalcommerce.org/#/c/229/

commit for 2. (A checkbox that says : "Allow checkout for anonymous users.") - https://code.drupalcommerce.org/#/c/230/

1. and 2. merged and completed on https://code.drupalcommerce.org/#/c/229/

in the previous commits, i changed the "access checkout" permission for anonymous.
i thought that the http://drupal.org/project/commerce_checkout_redirect replace the access denied for Anonymous users with a redirection to login.
maybe this could be a bug for this module, if there's no "access checkout" permission for anonymous.
this should be checked.

i removed all the permissions stuff and keep only the Commerce Checkout Redirect dependency for NOT("Allow checkout for anonymous users.")
https://code.drupalcommerce.org/#/c/229/

Merged in https://code.drupalcommerce.org/#/c/309/