Adding perl module File::pushd ad dependency for the CPAN::Reporter.

File::pushd does a temporary chdir that is easily and automatically reverted,
similar to pushd in some Unix command shells. It works by creating an object
that caches the original working directory. When the object is destroyed, the
destructor calls chdir to revert to the original working directory. By storing
the object in a lexical variable with a limited scope, this happens
automatically at the end of the scope.

(sno)