Updated the backup and restore DB for cassandra,mysql and nova-instances-data review comments and also
updated the code for centos and ubuntu

Change-Id: I8f17ea6c616975a1a0e7b67d9d71ec4bb29dfd0c
Merge "Updated the backup and restore DB for cassandra,mysql and nova-instances-data review comments and also updated the code for centos and ubuntu"
Merge remote-tracking branch 'upstream/master'