Handle correct spelling of card code input

The typo fix for the card code input can be found in the lastest
1.1 stable
Make use_existing_card labels clickable
Show card brand icon on existing cards list
commented out spree_core version dependency to allow for installation on 1.3
Merge pull request #11 from Scoutmob/pull-request/support-card-code-refs

Handle correct spelling of card code input
Merge pull request #12 from Scoutmob/pull-request/ui-tweaks-to-existing-cards-template

Pull request/ui tweaks to existing cards template
removes ruby 1.8
Merge pull request #13 from overworkedasian/master

Modification to allow installation on spree_core 1.3
fixes conflicts