Added VoucherNotApplied errorcode as outlined in Api docos
Merge pull request #91 from gregsochanik/voucher-error-code

Added VoucherNotApplied errorcode as outlined in Api docos
Added the Id property to map to the XML attribute returned from purchasing responses
Merge pull request #92 from danbadge/master

Making Id an accessible property on the responses from user/deliverItem and user/purchase/basket
Ignore failing track preview test

- This is failing due to a missing XML declaration.  The API is being fixed
  to reinstate it.
Merge pull request #94 from raoulmillais/ignore-track-stream-test

Ignore failing track preview test