ciao-down: Don't set no_proxy if no proxies have been defined.
ciao-down: Don't set no_proxy if no proxies have been defined.

This commit fixes a small issue in which the no_proxy variable was
set in the guest, even if proxies were not used or defined on the
host.

Signed-off-by: Mark Ryan <f16215f7acd0bd7fdc465539215bd574c785b062@intel.com>

01org/ciao,kaccardi/ciao,markdryan/ciao,kaccardi/ciao,markdryan/ciao,ciao-project/ciao,rbradford/ciao,rbradford/ciao,mcastelino/ciao,ciao-project/ciao,mcastelino/ciao,01org/ciao,tpepper/ciao,tpepper/ciao,tpepper/ciao,mcastelino/ciao