feature: initial setup for Stripe complete

Added gem and path for Stripe API.
Generated 'charges' controller for actions and views.
Added necessary resources for charges controller actions.
Created a purchase button linking to intermediary checkout page and
placed in the nav partial under conditional logic.
Styled link tag as button.
Configured Stripe intializer for test and production API in ENV.
Deleted welcome controller as outdated and unused controller.
feature: Added ability to purchase products via CC

Created receipt for after purchase.
Created and styled form for accepting payment for products.
Added class and instance methods in Product model to accommondate
Charges controller.
Incorporated ChargesHelper for view methods.
Created footer partial to access admin.
Made associations between models.
Merge pull request #3 from SeharaDesign/Checkout

Checkout