Flow is required to delete data from graphite

[rishubhjain]

Tendrl/gluster-integration#435

[rishubhjain]

As per discussion with @shtripat, we were able to finalise an approach to delete graphite data when a resource is deleted. The approach is as follows:

• When the flow is called with required details, the flow will look for the whisper file with that detail and move that file under archives at the cluster level. The archive will be stored with time stamp so as to reduce ambiguity.
  The whisper files are located at path /var/lib/carbon/whisper/
  Example: If volume vol_1 is deleted of cluster cluster_x then archive will be created at tendrl.clusters.cluster_x. level and inside archive a new folder will be created with time stamp like tendrl.clusters.cluster_x.archive.volumes_{timestamp}.vol_1
  If cluster is deleted then it will be archived at tendrl.clusters level like if suppose cluster_x is deleted then a new folder cluster_x_{timestamp} will be created tendrl.clusters.archive level and all the files under tendrl.clusters.cluster_x will be moved to tendrl.clusters.archive.cluster_x_{timestamp}.

[rishubhjain]

@r0h4n Please verify if the approach is appropriate