Not clearing known_hosts file

[dvenrao]

Versions:

• v2.0.10

Scenario:

Reusing ip address to vms

Steps to Reproduce:

kitchen create mutiple times reuses IP address

Expected Result:

kitchen create should success

Actual Result:

IP addresses found: repeating forerver

Work around:
add system("ssh-keygen -f ~/.ssh/known_hosts -R vm_ip") line at driver.rb file line number 478.
So it clears knows_hosts file entry signature before ssh login to new instance.