update file path regex for unicode letters

Created by: yms9654

When I upload a file, there is a issue if filename hava a unicode letters.(ex: korean or japanese or chinese characters). It can't pass file_path_regex. [a-zA-Z0-9_\-\.\/]

So how about this? [\p{L}\p{N}_\-\.\/] \p{L} means unicode letter and \p{N} is number. http://ruby-doc.org/core-2.1.7/Regexp.html#class-Regexp-label-Character+Properties