setup.py: append EC2_HOME/bin to PATH

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
setup.py: backup /etc/environment before override

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
setup.py: use standard EC2 packages on Ubuntu

Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
x64: explain where %rbp and %rbx are set

Signed-off-by: Elazar Leibovich <elazarl@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>