Fix \r\r\n and ignoring 'newlines' on win32

On win32 when the filename is given at instantiation time it was saving the files with \r\r\n at eol. If 'newlines' was set to '\n' it was saving files with \r\n. Changing file open to binary fixes this so the write() doesn't redo the line endings.
Correct type os.sep -> os.linesep for newlines

The doc said it uses os.sep, but it should read os.linesep for default for newlines
Merge https://github.com/MichaelHipp/configobj
#34, #14 - corrected and moved over doctests effected by writing out in binary mode; handling encoding that in a py2/3-compatible way