Support PayPal REST APIs
Format request payload
Updated testcase to validate request data
Validate item and address properties
Supported reauthorize for PayPal REST APIs
Validate shipping-address properties
Support PayPal-Request-Id http header
Added methods to lookup payment, sale, refund and credit-card in PaypalRestGateway
Catch HTTP exceptions and format response object
Helper method for sale_id and authorization_id
Resolve conflict with vindicia-gateway, because of PayPal constant
allow any version of nokogiri