UTF8 - Bug fix 

bug fix for UTF8 encoding, copied from:

http://stackoverflow.com/questions/3666412/php-excel-reader-problem-with-utf-8#answer-8297640
Fix 'Undefined index: MinWidth' issue.
Fix https://github.com/nuovo/spreadsheet-reader/issues/58
Merge remote-tracking branch 'bygiro/master' into 0.6.0-pre-alpha
Merge remote-tracking branch 'hongster/master' into 0.6.0-pre-alpha