Fixes #9 by introducing a new --eol option to force a line ending type

Makes use of `io.open` instead of standard `open`.
The `io.open` behaviour is actually default in Python 3.
Also update the README with the new --eol option.
PEP8 fixes and feedback from @fnd incorporated
Merge pull request #10 from dietmarw/eol

Fixes #9 by introducing a new --eol option to force a line ending type