Add mkhomedir augeas for Debian

RHEL/Centos/Fedora use authconfig to configure pam when --mkhomedir option is selected.
Actually there is a lack of support of --mkhomedir option in Debian/Ubuntu freeipa-client package (there is no authconfig on Debian, it's another mecanism to handle pam update)
That's why it could be usefull to have this functionnality implemented in puppet :)
Merge pull request #9 from aellert/patch-1

Add mkhomedir augeas for Debian