Major new features, various optims and bug fixes

This new 2.6.0 features some new features:

• Fingerprint support (see https://docs.mangopay.com/endpoints/v2.01/cards#e181_the-card-object and https://docs.mangopay.com/endpoints/v2.01/cards#e952_list-cards-for-a-fingerprint)
• Dispute docs and KYC docs consultation (if allowed, see https://docs.mangopay.com/endpoints/v2.01/dispute-documents#e220_list-a-disputes-documents)
• ShippingAddress support for Payin Paypal (beta)

Various optims has been done and bugs fixed:

• Wallet reporting enhancements
• Compatibility with more PHP versions
• Improve Travis build and tests