Remove password based etcd authentication

[mbukatov]

Since using password based etcd authentication mode makes whole Tendrl stack extremely slow, with etcd itself consuming about 95% of cpu processing power, changes of the etcd auth configuration needs to be made across Tendrl stack.

Related issues concerned with etcd password auth:

• Enable ETCD authorization and authentication api#262
• Enable ETCD authorization and authentication commons#721

Since the root cause seems to be etcd issue: etcd-io/etcd#3223 (comment), the etcd auth should be removed. This is blocked by: Tendrl/api#294

This basically boils down to reverting changes introduced in #34

[mbukatov]

Removal verified by @r0h4n during A daily meeting of Tendrl developers today. Updates wrt cert based auth will be provided in tendrl issues linked in description of this issue.

[mbukatov]

Since Tendrl/api#295 has been merged, I'm going to just change the default for https://github.com/Tendrl/tendrl-ansible/milestone/2 and move this password auth removal issue into https://github.com/Tendrl/tendrl-ansible/milestone/3.

[mbukatov]

Now we have a new cert base approach details drafted here: https://github.com/Tendrl/documentation/wiki/Tendrl-with-a-secure-etcd-cluster so I will proceed with removing password based auth.

[mbukatov]

Fixed by 5428aad