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

Closes #31
Resave with excess whitespace removed
Extract commonality about error handling into functions, encapsulated in a Handlers namespace.
Allow arbitrary error handlers to .walk. Enables a workaround for #73.
Update changelog
Added tag 5.3 for changeset 83dcd6b47278
Bumped to 5.4 in preparation for next release.
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
Update setup.py and tox.ini to specify py.test for testing
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