At the same time, I've renamed tmpfilesd config file to static name
"ipa.conf" instead of using package-specific name. It had no purpose
and just complicated build and packaging.

Variable substitution into configuration has to be done in Makefile
and not in Autoconf as documented in:
Autoconf v2.69 manual chapter 4.8.2 Installation Directory Variables:
  ... Most of these variables have values that rely on prefix or
  exec_prefix. ... Similarly, you should not rely on AC_CONFIG_FILES
  to replace bindir and friends in your shell scripts and other files;
  instead, let make manage their replacement.

https://fedorahosted.org/freeipa/ticket/6418

Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>

* Adds ipa_memcached SystemV initscript

* Adds ipa_memcached service file and tmpfiles.d/ipa.conf
  to recreate /var/run/ipa_memcached on reboot.

* Adds ipa_memcached config file

* Adds memcacheinstnace.py to manage ipa_memcaced as
  as SimpleService object.

* Updates the IPA service list to include ipa_memcached,
  at service positon 39, httpd is position 40

* Updates the spec file:
  - requires the memcached daemon and python client
  - installs service or initscripts depending on OS
  - installs config file
  - creates /var/run/ipa_memcached directory

* Modifies ipa-server-install to install ipa_memcached