added oauth flow sequence diagram (with login and approval)
added oauth flow sequence diagram (with login and approval)

sequenceiq/cloudbreak,hortonworks/cloudbreak,hortonworks/cloudbreak,hortonworks/cloudbreak,sequenceiq/cloudbreak,sequenceiq/cloudbreak,sequenceiq/cloudbreak,hortonworks/cloudbreak,hortonworks/cloudbreak,sequenceiq/cloudbreak,hortonworks/cloudbreak