Merge pull request #25 from dranes/omnipay-v3

Add support to Omnipay v3

Merge pull request #24 from Korri/patch-1

 Send CVV2 with card reference transactions

Merge pull request #19 from RobvH/add-reference-sale-support

Implement reference purchases

Merge pull request #12 from code-pilots/dev-master

Send some missing fields to PayPal

Merge pull request #9 from delatbabel/add-currency

Fixes #5

Merge pull request #7 from jtgrimes/feature-void-transaction

void transaction

Update .travis.yml

PSR-4

Fix name value pair encoding

Update dependencies