Description of problem:
Create user API call requires to specify parameters `password` and `password_confirmation`. There should be provided only `password` parameter and confirmation of matching passwords should be held on the front-end side.

Version-Release number of selected component (if applicable):
tendrl-selinux-1.5.3-2.el7rhgs.noarch
tendrl-commons-1.5.4-3.el7rhgs.noarch
tendrl-api-httpd-1.5.4-2.el7rhgs.noarch
tendrl-grafana-selinux-1.5.3-2.el7rhgs.noarch
tendrl-ansible-1.5.4-1.el7rhgs.noarch
tendrl-node-agent-1.5.4-3.el7rhgs.noarch
tendrl-ui-1.5.4-3.el7rhgs.noarch
tendrl-grafana-plugins-1.5.4-4.el7rhgs.noarch
tendrl-notifier-1.5.4-2.el7rhgs.noarch
tendrl-api-1.5.4-2.el7rhgs.noarch
tendrl-monitoring-integration-1.5.4-4.el7rhgs.noarch


How reproducible:
100%

Steps to Reproduce:
1. Check in Tendrl that there is no user called thardy.
2. Send API call like this (with valid access token):
```
curl -H 'Content-Type: application/json' -H 'Authorization: Bearer
d03ebb195dbe6385a7caeda699f9930ff2e49f29c381ed82dc95aa642a7660b8'
-XPOST -d '{"name":"Tom Hardy", "username":"thardy",
"email":"thardy@tendrl.org", "role":"admin", "password":"pass1234",
"email_notifications": true}'
http://127.0.0.1/api/1.0/users
```
3. Send API call like this (with valid access token):
```
curl -H 'Content-Type: application/json' -H 'Authorization: Bearer
d03ebb195dbe6385a7caeda699f9930ff2e49f29c381ed82dc95aa642a7660b8'
-XPOST -d '{"name":"Tom Hardy", "username":"thardy",
"email":"thardy@tendrl.org", "role":"admin", "password":"pass1234",
"password_confirmation":"pass1234","email_notifications": true}'
http://127.0.0.1/api/1.0/users
```

Actual results:
API call from step 2 fails because there was not provided parameter `password_confirmation`. API call from step 3 succeeds.

Expected results:
API call from step 2 should succeed.

Additional info:
https://github.com/Tendrl/api/blob/master/docs/users.adoc#create-user