Revise the handling of the 401 license Exception
Revise the handling of the 401 license Exception

Revise the handling of the CredentialsError exception raised by the
API during `set_api`, in order to make the output less verbose by just
showing the last Exception instead of the full chained list. For the
rest of Exceptions, the original behaviour is preserved.

QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py,atilag/qiskit-sdk-py,QISKit/qiskit-sdk-py,atilag/qiskit-sdk-py,atilag/qiskit-sdk-py