Do not use multiline strings for the 'stack_sshkey' option
Do not use multiline strings for the 'stack_sshkey' option

Using multiline strings for the 'stack_sshkey' option results in the
following Puppt error:

Parameter key failed on Ssh_authorized_key[stack]: Key must not contain whitespace:

Change-Id: I41da285086af3fd90fb4887cd643d17ec52806a8

nexusz99/devstack-vagrant,AlessandroCopler/TestVagrant,unibg-seclab/devstack-vagrant,AlessandroCopler/test_esc,olivierlemasle/devstack-vagrant,j4/devstack-vagrant,meniy/Vagrant,AlessandroCopler/TestVagrant,openstack-dev/devstack-vagrant,nexusz99/devstack-vagrant,unibg-seclab/devstack-vagrant,verdurin/devstack-vagrant,meniy/Vagrant,Sunnepah/devstack-vagrant,olivierlemasle/devstack-vagrant,verdurin/devstack-vagrant,j4/devstack-vagrant,openstack-dev/devstack-vagrant,meniy/Devstack-Vagrant,meniy/Devstack-Vagrant,meniy/Vagrant,unibg-seclab/devstack-vagrant,AlessandroCopler/test_esc,Sunnepah/devstack-vagrant