Allow log_dir to be set to false in order to disable file logging

This backward compatible commit allows a user to disable logging to
a directory for example if using syslog logging.

Change-Id: I8b496c311b9f26cab64c38d1cfd545784dfc7cab
Related-bug: #1269482
(cherry picked from commit 2b35c1a04ce6f28f700971c31d18af88b65a089e)
Havana: Fixtures: fix keystone branch name

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

Change-Id: If4a484010e4f8a3fd8aa6f0f5434943194637331
Merge "Allow log_dir to be set to false in order to disable file logging" into stable/havana
Merge "Havana: Fixtures: fix keystone branch name" into stable/havana
Allow db fields configuration without doing the dbsync

This commit allows one to configure the db fields without running the actual
dbsync command. It remains compliant with the current implementation, leaving
exec {'ceilometer-dbsync': in the catalog. One, now, can decide if it wants
the dbsync to take place or not.

This is useful when one picks mongodb as a backend and wants to use replicaset
This way it can scale horizontally and painlessly using the initSync feature
of mongodb. With this pattern one can add new member of the replica set
easily.

Change-Id: I8618bb385147176512fbda1540ba75ac95fccbf1
(cherry picked from commit 1aa1d795f0c06bb5266886b8599814e61fbef3f3)
Define $user referenced in db.pp

In db.pp, in the exec 'ceilometer dbsync' ressource the user
is supposed to be $::ceilometer::params::user, but it was
not defined.

(cherry picked from commit e6c191194312935ea01c97ae667bf3ea1a912f81)

Conflicts:
	spec/classes/ceilometer_db_spec.rb

Change-Id: I888be405f418932c0e46ce8e82486755d36fc7bf
Merge remote-tracking branch 'upstream/stable/havana' into havana