Adding composer.json
Adding OmniKassaOrder
Adding tests for merchantId
Adding method for secret key
Adding currency
Adding Travis configuration file
Adding interfaceVersion
Adding creation of OmniKassaOrder object in setUp method
Adding normalReturnUrl
Adding automaticResponseUrl
Complying with PSR-2
Adding new argument for specific Exception messages
Adding requirement for PHP version
Adding keyVersion
Adding transactionReference
Adding amount
Adding orderId
Adding customerLanguage
Adding payment methods
Adding expiration date for payment