Add encrypt_file and decrypt_file utility functions.

We will use them to encrypt the replica file so that we can
transport it over more safely.
It contains sensitive data, by encrypting it we assure that
even if a distracted admin leaves it around it cannot be accessed
without knowing the access passphrase (usually the Directory Manager
password)

Along the way fix also ipautil.run which was buggy and not passing
in correctly stdin.

Add dependency for gnupg in spec file

ipa-python/ipa-python.spec.in

@@ -10,7 +10,7 @@ Source0:        http://www.freeipa.org/downloads/%{name}-%{version}.tgz
 BuildRoot:      %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
 BuildArch: 	noarch
 BuildRequires:  python-devel
-Requires:       python-kerberos
+Requires:       python-kerberos gnupg
 
 %{!?python_sitelib: %define python_sitelib %(%{__python} -c "from distutils.sysconfig import get_python_lib; print get_python_lib()")}