Make px_mkfw.py and px_upload.py compatible with both python 2.7 and 3.3

Tools/px_mkfw.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 ############################################################################
 #
-#   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+#   Copyright (C) 2012, 2013 PX4 Development Team. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
@@ -60,7 +60,7 @@ def mkdesc():
 	proto['description']	= ""
 	proto['git_identity']	= ""
 	proto['build_time']	= 0
-	proto['image']		= base64.b64encode(bytearray())
+	proto['image']		= bytes()
 	proto['image_size']	= 0
 	return proto
 
@@ -99,12 +99,12 @@ if args.description != None:
 if args.git_identity != None:
 	cmd = " ".join(["git", "--git-dir", args.git_identity + "/.git", "describe", "--always", "--dirty"])
 	p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE).stdout
-	desc['git_identity']	= p.read().strip()
+	desc['git_identity']	= str(p.read().strip())
 	p.close()
 if args.image != None:
 	f = open(args.image, "rb")
 	bytes = f.read()
 	desc['image_size'] = len(bytes)
-	desc['image'] = base64.b64encode(zlib.compress(bytes,9))
+	desc['image'] = base64.b64encode(zlib.compress(bytes,9)).decode('utf-8')
 
 print(json.dumps(desc, indent=4))

Tools/px_uploader.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 ############################################################################
 #
-#   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+#   Copyright (C) 2012, 2013 PX4 Development Team. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
@@ -102,7 +102,7 @@ class firmware(object):
             0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
             0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
             0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d])
-        crcpad = bytearray('\xff\xff\xff\xff')
+        crcpad = bytearray(b'\xff\xff\xff\xff')
 
         def __init__(self, path):