ENH: added functionality to set/get operator name on application level
- name will be stored under QSettings "OperatorName"
for the reference: https://github.com/QIICR/QuantitativeReporting/issues/201#issuecomment-371258260
for the reference: https://github.com/QIICR/QuantitativeReporting/issues/201#issuecomment-371258260