py3: Fix encoding and use sys.stdin.buffer

* exc.py: Encode body in response before calling replace over it.
* http.py: prepend the bytes literal to the empty string or else
  we hit bug 1342080 again in python 3.
* utils.py: Use sys.stdin.buffer in python 3.

Change-Id: Ieefb8c633658e507486438e5518c5d53e819027d

glanceclient/exc.py

@@ -16,6 +16,8 @@
 import re
 import sys
 
+import six
+
 
 class BaseException(Exception):
     """An error occurred."""
@@ -177,6 +179,8 @@ def from_response(response, body=None):
         details = ': '.join(details_temp)
         return cls(details=details)
     elif body:
+        if six.PY3:
+            body = body.decode('utf-8')
         details = body.replace('\n\n', '\n')
         return cls(details=details)