Also input password manually when executing dockerswarm workload

Description
===========
The 'password' for ssh connection is already asked when `scp`
TLS certifications to swarm node. The ssh-key maybe not prepared OK.

Steps to reproduce
==================
* Clone the latest source
git clone https://github.com/openstack/interop-workloads.git in-wo-m
* Create my cloud's vars file
* Execute ansible-playbook
ansible-playbook -e "action=apply env=inspur password=interop" site.yml

Expected result
===============
SUCCESS

Actual result
=============
Failure

Environment
===========
1. interop-workloads version
# git log
commit fa360ae63c171fc8ce2cc270099fff3e60bc5ae7
Author: Daniel Mellado <email address hidden>
Date: Wed Feb 8 16:46:22 2017 +0100

    Add specs to documentation

    This commit adds a spec folder within documentation. This would be
    moved under its own project if it starts growing big enough.

    Change-Id: I54b8402b35ff72577f1b949d9a081752cb08a13b

2. Which workload did you use?
dockerswarm

Logs
===========
TASK [prov_apply : Transfer configureation] ************************************
Password:
core@172.23.28.215's password: