Make ansible ask for sudo password

If the user used to install and run bifrost can't run sudo
passwordless, the bifrost-cli appends the --ask-become-pass option
that makes ansible ask for the BECOME password, used to run
commands with become set to true.

Change-Id: I7148243b19baa8bfdd652827a9280d469622e3f3

bifrost/cli.py

@@ -231,8 +231,7 @@ def check_for_root():
             '[ $(whoami) == root ] || sudo --non-interactive true',
             shell=True, stderr=subprocess.DEVNULL)
     except subprocess.CalledProcessError:
-        # TODO(dtantsur): tell ansible to ask for password
-        sys.exit('Sudo without password is required for Bifrost')
+        COMMON_PARAMS.append('--ask-become-pass')
 
 
 def main():