Added file extension constraints.
Update README.md with allowedfileextensions example
Added error example for FileExtensionNotAllowed
file to files[fileIndex]
allowedextension typo
Fix loops
paramname can be a function
Merge pull request #108 from rjralgar/master

Allow restrictions to be put on file extensions
Merge pull request #127 from LawrenceLeung/master

Support function in paramname
Document paramname change