Remove unused DocDataPaymentMethodSerializer.
Remove old commentted out code in orders.js.
Cleanup Order Payment flow doc.
Add supports_single as config parameter for DocData payment methods.

Also add direct debit config to default settings.
Cleanup variable name in DocData payment adapter.
Add API for DocData DirectDebit.
Some voucher -> giftcard branding fixes.
Merge pull request #310 from benkonrath/voucher-giftcard-branding-fixes

Some voucher -> giftcard branding fixes.
Use Uppercase for Vouchers.
Voucher redeem  styled
Merge pull request #313 from prashantpalikhe/buttons

Voucher redeem  styled
Merge pull request #311 from benkonrath/direct-debit-api

Direct debit api
Merge pull request #312 from benkonrath/voucher-uppercase

Use Uppercase for Vouchers.