Remove redundant shebangs from files that are not used as scripts.

https://fedorahosted.org/freeipa/ticket/3853

https://fedorahosted.org/freeipa/ticket/3671
https://fedorahosted.org/freeipa/ticket/3672

Old versions of SSSD do not directly support cross-realm trusts between IPA
and AD. This patch introduces plugins for the ipa-advise tool, which should
help with configuring an old version of SSSD (1.5-1.8) to gain access to
resources in trusted domain.

Since the configuration steps differ depending on whether the platform includes
the authconfig tool, two plugins are needed:

* config-redhat-sssd-before-1-9 - provides configuration for Red Hat based
  systems, as these system include the autconfig utility
* config-generic-sssd-before-1-9 - provides configuration for other platforms

https://fedorahosted.org/freeipa/ticket/3671
https://fedorahosted.org/freeipa/ticket/3672

Now the list of available advices is neatly formatted:

-------------------------
List of available advices
-------------------------
    config-fedora-authconfig : Authconfig instructions for configuring Fedora
                               18/19 client with IPA server without use of SSSD.

The advice header printing has been reformatted to conform with the changes.

The comments logged through AdviceLogger are now wrapped up to 70
characters. This change has been documented in the docstrings.

Provides a pluggable framework for generating configuration
scriptlets and instructions for various machine setups and use
cases.

Creates a new ipa-advise command, available to root user
on the IPA server.

Also provides an example configuration plugin,
config-fedora-authconfig.

https://fedorahosted.org/freeipa/ticket/3670