fix use of LOCALMACHINE if no python-apt is available

..also replace LOCALMACHINE by localhost for python-apt fallback code

Signed-off-by: Manuel Traut <manut@linutronix.de>
add apt.conf.mako

needed by buildenv to configure the LOCALMACHINE proxy override

Signed-off-by: Manuel Traut <manut@linutronix.de>