Fix SerializerUnicode to split unquoted newlines

This provides a fix to issue #131. The `split_unquoted_newlines()`
function added to the utils module handles the splitting of the string
by performing a simple iteration of the string passed in and splitting
on unquoted CR, LF, or CR+LFs as they are found.
Merge pull request #132 from petronius/master

Fix SerializerUnicode to split unquoted newlines