Don't use a template for nsswitch.conf

It will more than likely get into a never-ending fight with
authconfig. authconfig does not currently handle the sudoers line
though so append this if it is missing and then add or remove sss
(not ldap!) as necessary. Finally, the ldap_sudo attribute should be a
real boolean, not a string. Fixes #12.
Always restart sssd after changing sssd.conf

This was not happening under RHEL. We don't necessarily need to
restart it immediately either.
Use ldap_tls_cacertdir rather than ldap_tls_cacert

ldap_tls_cacertdir expects a directory containing individual
certificate files ending in .0. RHEL does not install these and yet
the default attribute value was specific to RHEL. It is least
confusing to use ldap_tls_cacert on all systems and point it at the
bundle file. Both RHEL and Debian include utilities to manage this
file.
Merge pull request #15 from yakara-ltd/restart_sssd

Always restart sssd after changing sssd.conf
Merge pull request #16 from yakara-ltd/ldap_tls_cacert

Use ldap_tls_cacertdir rather than ldap_tls_cacert
Merge pull request #14 from yakara-ltd/no_nsswitch_template

Don't use a template for nsswitch.conf