Generate heat.conf.sample config file

Upstream removed the sample config file in the source tree, so it has to
be generated now:
https://github.com/openstack/heat/commit/cf0b59953cedb6aeb5d182aa567e2cb928843ca6

Though the above commit recommends using "tox -egenconfig", the direct
execution of generate_sample.sh was used instead. See this thread for
more info:

http://lists.openstack.org/pipermail/openstack-operators/2014-December/005690.html

Change-Id: I8ad3002df126b01e474fc2ab726f5d90d845e1df
Change systemd service files to not use logfile

Resolves: rhbz#1083057

Change-Id: I5ec4adfa0f5c606a44574e13b0c48a4e276d1759