Add attribute to disable glance-replicator

There are cases where users may wish to disable the glance-replicator
script, e.g. when using a distributed filesystem for the Glance image
directory. This commit allows for setting node['glance']['replicator']
['enabled'] in the node attributes.
Disable replicator when using an alt. storage type

There is no point in enabling the replicator script if Glance
is using an alternate storage method.
Merge pull request #162 from DavidWittman/disable-glance-replicator-rebase

Merged automatically by jenkins after successful build test