Various updates

Changes:

• fixes incorrect float32 rounding (@Seklfreak )
• add AdditionalData to Authorize (@hfajunakaliantiga )
• notification signature feature (@colonel-sanders)
• add FraudResult to AuthoriseResponse (@hfajunakaliantiga )
• fix Travis CI job + added tests and verifications for Go 1.12, 1.13, 1.14

Adding go modules support

Update:

• Add go modules support

Thanks to @Seklfreak for contribution

API update + ExecuteThreeD

Updates

• ExecuteThreeD option added to AdditionalData structure
• Technical cancellation API call
• Support of Go 1.10 and 1.11 added

Update adyen endpoint URLs

Update adyen endpoint URLs

Due to the change in Adyen, we need to update endpoint urls:

Changes:

• https://%s-%s-pal-live.adyen.com/pal/servlet -> https://%s-%s-pal-live.adyenpayments.com/pal/servlet
• https://%s-%s-checkout-live.adyen.com/services/ -> https://%s-%s-checkout-live.adyenpayments.com/services/

First release v0.1

Adyen API implementation in Go

APIs covered:

• Authorize
• Recurring
• Modification (cancel, capture, refund, e.t.c)
• Notifications
• Checkout API