allow delegation of credentials between vms

[ThomasSandholm]

In many cases the vm you are creating may want to perform operations on behalf of you and therefore needs access to your funds. The simplest way to achieve this is to copy over the .tycoon directory and create a fresh .ssh directory, it is however error prone and not optimally secure. A more advanced protocol may be to setup a fresh user on the new vm that has a bank account sponsored by the user creating the vm with some initial balance. It could be done as part of the host create_account command as an option like -oDelegateCredential=<initial balance>