[FIX] REST tool handle DEV-44 in all cases

Previous "fix" for this issue didn't work in one particular case:
1. Choose a command that uses the POST method
2. Change method to GET
3. Change command to one that uses GET method
4. Change method to POST
---> POST body from previous command remains (despite being set to "", it didn't stick.)

This change (calling refresh on the cm_request object) should fix that.