'about_file_path" does not support spaces

[chinyeungli]

This is a bug. The 'about_file_path' should have space support

[chinyeungli]

From the spec

    From spec :
        A file name can contain only these US-ASCII characters:
        - digits from 0 to 9
        - uppercase and lowercase letters from A to Z
        - the _ underscore, - dash and . period signs.

@pombredanne should we support spaces in filename?

[chinyeungli]

@pombredanne I think supporting spaces in filename is appreciated. Let me know if you disagree.

[chinyeungli]

Note that we have tests which treat space as invalid character

def test_check_file_names_with_invalid_chars_return_errors and def test_invalid_chars_with_space(self):