[Core] [WebBundle] Implemented Guest checkout
Fixed code style.
Fixed fatal on checkout.
Improved guest customer info in admin.
Merge remote-tracking branch 'upstream/master' into GH90-Implementing-guest-checkout
Merge remote-tracking branch 'origin/master' into GH90-Implementing-guest-checkout
Fix code after feedback, add ability to disable guest orders
Fix test
Merge pull request #1816 from torinaki/GH90-Implementing-guest-checkout

[Core] [WebBundle] Implemented Guest checkout