Checkout process with mercado pago
- Buy order when user selects Pay
- Using MP modal for checkout -> i had to change navbar z-index 
- request configuration (only credit cards)
Adds Collection Main Form
Merge branch 'DEV' into CollectionsManager

Conflicts:
	app/controllers/Application.java
Refactors manually some classes
Action Delete example
Creates Collections ABM Structure
Creates Edit modal
Adds creation of new collections
Merge branch 'DEV' into CollectionsManager
Adds modal to list collection's items
Adds EditCollection function and generates random image from item
without repeating
Adds AM items from collection
Fixes items from collection list and adds delete mock item from
collection
Esthetically improves garment details' view aun UI.
Adds item to collection association
Adds delete reference of collection from item
added pointsEnabled in Seller
added to BuyOrder: State(default PAYMENT_PENDING on creation) +
points(used/earned) + size
Stock returns a Map with available Size options for an Item
in initial data: one Seller set with pointsEnabled and another with
pointsDisabled