[-] BO : fix bug with utf8 symbols in image urls during import

hello, problem is described in the article http://blog.belvg.com/importing-images-with-regional-symbols-in-the-file-names-in-prestashop.html#comment-11652

I implemented code fix from my comment (see copyImg() method), but also noticed there were some code sniffer problems, so fixed them too. 

Please, advice what is the best in this case: make 2 different pull requests for CS fixes and url encode fix or you can use this commit?
https://github.com/PrestaShop/PrestaShop/pull/2176