additions to tools.qi
additions to tools.qi

- changed ‘basis’ keyword to ‘method’ in vectorise, devectorize
- fixed bug in pauli devectorize
- added choi_to_rauli function

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