AbstractChunkedController: phpdoc fix

Fix param naming as of PHPStorm inpections warnings
and add param types to phpdoc
Composer: Added require_dev phpunit/phpunit 3.7.*

Just for avoid old and ugly pear
ErrorHandlerInterface - tune method param types

ErrorHandlerInterface::addException($response, $exception)

Replace $response type ResponseInterface with AbstractResponse
because ErrorHandlerInterface descendants newer uses the ResponseInterface::assembly() method
but uses AbstractResponse::addToOffsetMethod so ResponseInterface parameter does not guarantees
a typesafe method call, but AbstractResponse does!

Replace UploadException $exception with \Exception
which allow add any required exception in controllers
Remove cache before executing tests
Introduced getFiles function on AbstractController

This method will flatten a given file bag and extract all UploadedFile instances.
Addresses: #28 & #29.