Havana: Fixtures: fix keystone branch name

Solve issue: « fatal: ambiguous argument 'stable/havana': unknown
revision or path not in the working tree. »

Change-Id: I8dc5eac46d16053f587ebf56e558025ca63c3d4b
Allow log_dir to be set to false in order to disable file logging

This commit allows a user to disable logging to a directory (for
example if syslog is enabled, in order to not log twice).

Conflicts: spec/classes/heat_init_spec.rb

Closes-bug: #1282296
(cherry picked from commit 603fb207959fe6fdeca2029c29c18342fc2d6b60)
Change-Id: I814bf8199fcf57f976e95b9bbf872478694b9d3e
Merge branch 'stable/havana' of https://github.com/stackforge/puppet-heat into havana

Conflicts:
	spec/classes/heat_init_spec.rb