Update StringUtil.java

Fixed so that it properly recognises unicode spaces.  Was reporting " " as not whitespace.  
These "strange" spaces can be found in the search results found here: http://www.cls.ioe.ac.uk/Bibliography.aspx?sitesectionid=647&sitesectiontitle=Bibliography&d=1&yf=&yt=&a=&s=NCDS&o=&j=&page=2