feature 1429 secure key management

 deploy proxy charm first
 wait blocked o ready, exec get-ssh-public-key, generate-ssh-key
 deploy VMs, inyect ssh-keys at VM
 exec config initial primitives,
 exec verify-ssh-credentials
 exec rest of initial primitives

Change-Id: I8c9c908ab09d70061744677ae23e9d93b41dcdc7
Signed-off-by: tierno <alfonso.tiernosepulveda@telefonica.com>