Fix Python3.2 compatibility

.travis.yml

@@ -4,6 +4,7 @@ python:
   - "3.3"
 # command to install dependencies
 install:
+  - "apt-get install -y libacl1-dev"
   - "pip install --use-mirrors Cython"
   - "pip install -e ."
 # command to run tests

attic/platform.py

@@ -1,6 +1,6 @@
 import os
 
-platform = os.uname().sysname
+platform = os.uname()[0]
 
 if platform == 'Linux':
     from attic.platform_linux import acl_get, acl_set, API_VERSION

setup.py

@@ -9,7 +9,7 @@ versioneer.versionfile_build = 'attic/_version.py'
 versioneer.tag_prefix = ''
 versioneer.parentdir_prefix = 'Attic-' # dirname like 'myproject-1.2.0'
 
-platform = os.uname().sysname
+platform = os.uname()[0]
 
 min_python = (3, 2)
 if sys.version_info < min_python: