Throws IOError if protofile contains path delimiters

[dff180]

When the protofile contains path delimiters it will cause IOErrors since it tries to create a file in a directory which does not exist.

Here's a fix: https://github.com/dff180/Protod/commit/b6f9a69279450cff1f3261ef4b8852c12540ce5e

[pcolby]

Thanks!! Was exactly what I needed! :)