Merge pull request thephpleague#83 from academe/master

A few additional details on acceptNotification()

Merge pull request thephpleague#53 from dignat/master

Filter invalid characters from basket item names, handle multiple discounts and no discounts.

Merge pull request thephpleague#52 from academe/master

Issue thephpleague#46 remove redundant validation check.

Merge pull request thephpleague#28 from academe/protocol3

Support SagePay Protocol v3.00

Update .travis.yml

PSR-4

Response::getTransactionReference() should always return value even i…

…f TxAuthNo is not present

Update dependencies