Add reset bmc command

Change-Id: I3d027303667ade4ad3790c5c614ea01f2ead6e39

pyghmi/ipmi/command.py

@@ -267,6 +267,13 @@ class Command(object):
         else:
             return lastresponse
 
+    def reset_bmc(self):
+        """Do a cold reset in BMC
+        """
+        response = self.raw_command(netfn=6, command=2)
+        if 'error' in response:
+            raise exc.IpmiException(response['error'])
+
     def set_bootdev(self,
                     bootdev,
                     persist=False,