- make the build of the locator plugin optional
- added a man page for the locator plugin
- use krb5.h if krb5/krb5.h cannot be found
- added alternatives for missing functions
- set -DDBUS_API_SUBJECT_TO_CHANGE if libdbus version
  is lesser than 1.0.0

Older python versions (such as that used in RHEL5) do not have a
python-config executable to report CFLAGS and LIBS. In order to
support such versions of python, we will duplicate the logic that
python-config would have performed directly in our configure
script

Implement a set of python bindings for the sysdb with feature set
similar to what is available in the tools. The primary
consumers would be applications like system-config-users.

Resolves: Ticket #102

PCRE_DUPNAMES is a new feature of libpcre 7. It is used in sssd to
make the splitting of fully qualified user names more flexible.

Changes the configure process so that configure errors out if lacks the
tools necessary to build manual pages (like xsltproc). Also adds a check
for required URI of the docbook XSL templates using the xmlcatalog tool.

This patch adds ares parsing functions that are not yet upstreamed
together with a private ares header file (ares_dns.h) that contains
some necessary macros for parsing common structures in the replies.

Users of these two parsing functions must also include the header files
ares_parse_{srv,txt}_reply.h that contain the function and structures
declarations that should eventually end up in upstream ares.h

Integrates the c-ares asynchronous resolved library into SSSD.