fixes #162. Back porting with a cut and paste
Check that pathinfo() has returned an extension

Prevent the notice that is generated when pathinfo() doesn't return an
'extension' element in Zend_Validate_File_Extension.

Fixes #287
Merge pull request #294 from akrabat/issue-287

Fixes #287 - Check that pathinfo() has returned an extension
Merge pull request #278 from jeremyquinton/issue-162

Fixes #162 - Validate quoted local part of email addresses