Add locateName() and getFromName() to PHPExcel_Shared_ZipArchive, Modify...

[adamriyadi]

• Add locateName() and getFromName() to PHPExcel_Shared_ZipArchive.
• Modify PHPExcel_Reader_Excel2007 to use zipClass from PHPExcel_Settings::getZipClass()

[MarkBaker]

Thanks for the PR... the only thing I've modified is to suppress the check for the $zipClass, because the ZipArchive class won't necessarily have been autoloaded prior to the first instantiation, so will throw an exception at that point. I'll take a look at how I can modify that check