Dont check lbaas agent if we are not using it

Need to break the lbaas sensu checks out as we may not alway need them.
Fix broken CI

We need to define this in defaults.yml because we are referencing these
defaults cross-role.
Merge pull request #338 from craigtracey/lbaas_feature_flag

Dont check lbaas agent if we are not using it
Merge pull request #339 from craigtracey/fixci

Fix broken CI
Merge remote-tracking branch 'upstream/master' into trusty-hwraid