Update RequestInterface.php

Added getJsonRawBody() to Http\RequestInterface as it was missing
Merge pull request #173 from aledelgo/patch-1

Add getJsonRawBody() to RequestInterface.php
Fixing issue #94 (migration of unsigned columns)
Merge pull request #175 from kevin-bartl/master

Fixing issue #94 (migration of unsigned columns)
Merge branch 'master' of https://github.com/phalcon/phalcon-devtools