Check for buffer and use memoryview if missing

Python 3 does not implement buffer.  Use memoryview
as a standin if buffer would induce a NameError.

Change-Id: Id36e8253fffee9dc22bd982e00554f1c25bc95b4

pyghmi/ipmi/command.py

@@ -33,6 +33,10 @@ try:
     xrange
 except NameError:
     xrange = range
+try:
+    buffer
+except NameError:
+    buffer = memoryview
 
 
 boot_devices = {

pyghmi/ipmi/events.py

@@ -26,6 +26,10 @@ try:
     xrange
 except NameError:
     xrange = range
+try:
+    buffer
+except NameError:
+    buffer = memoryview
 
 
 psucfg_errors = {

pyghmi/ipmi/oem/lenovo/handler.py

@@ -48,6 +48,10 @@ try:
     xrange
 except NameError:
     xrange = range
+try:
+    buffer
+except NameError:
+    buffer = memoryview
 
 inventory.register_inventory_category(cpu)
 inventory.register_inventory_category(dimm)

pyghmi/ipmi/private/util.py

@@ -21,6 +21,10 @@ try:
     xrange
 except NameError:
     xrange = range
+try:
+    buffer
+except NameError:
+    buffer = memoryview
 
 
 def decode_wireformat_uuid(rawguid):