Handle EconomyResponse objects from Vault on all transactions.

Vault's EconomyResponse was ignored for some cases, such as money transfers and deposits.
This would cause money to get lost if a transfer failed. This change refunds the initiatior of a transfer and notifies them of the failure.

Failing transfers can happen often when using economy plugins based on physical currency, such as Gringotts,
for example when no space is available in an account.
Merge pull request #201 from jastice/econfix

Handle EconomyResponse objects from Vault on all transactions.