fix: in some image, ``/root/.ssh`` does not exist leading to charm failure.

precise/base-0k/hooks/install

@@ -122,6 +122,8 @@ EOF
 cp src/etc/ssh/lxc_git_access_id_rsa /etc/ssh/lxc_git_access_id_rsa
 chmod 0600 /etc/ssh/lxc_git_access_id_rsa
 
+mkdir -p ~/.ssh
+
 cat <<EOF > ~/.ssh/config
 
 Host git.0k.io
@@ -145,4 +147,3 @@ cd /opt/apps &&
 git clone git.0k.io:/var/git/0k/git-sub &&
 ln -sf /opt/apps/git-sub/git-sub /usr/lib/git-core/
 )
-