chown now accepts names in addition to id for user and group

Closes #31
Drop support for Python 2.5
Remove Python 2.5 reference from tox.ini
Use literal octals and depend on with statement present in Python 2.6

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extra : rebase_source : 711f30035df62de9bc95edc76644c5d916e01471
Update PY3 test to avoid numeric indexes

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extra : rebase_source : 19b258f25ae4e5880dd2416a74ac1e28cbe157ce
Use 'string_types' and 'text_type' using conventions from six

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extra : rebase_source : 390c67fc27c2e68f87bf77854d60432e14ed22cf
Use PY2 indicator for getcwdu

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extra : rebase_source : cd0f234b42aafaa61c7c4fc442b22167bfa771b3
Implement 'u' wrapper as simple lambda.

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extra : rebase_source : 30d8c08fe43ea597873ca688f62b2774fed065ec
Use builtins to avoid linter warnings

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extra : rebase_source : 35b1b75f9ff5c5bd8026164ef6b6e48ca18b7324
Include registration of surrogate_escape handler in Python 2/3 section.

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extra : rebase_source : d6ac9c891323dd28d7d28ff5be4c5ce0d8fb4435
Modernize example

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extra : rebase_source : 0ae0bc67272b0c5752441ac07fb832dadabd5bac
Merge pull request #75 from gazpachoking/pytest

Update setup.py and tox.ini to specify py.test for testing
Merge with master
Want the __builtin__ module (only available on Python 2).
Add support for running tests with pytest-runner.
Add trailing comma for improved future diff readability.
Require setuptools for build/setup.
Update changelog to reflect 5.3 addresses #56.
Bumped to 6.0 in preparation for next release.
Added tag 6.0 for changeset 2d5f08983462