Make DEBUG come from the environment instead of just a constant

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
move netmanager under the newly created bin/ namespace

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
several changes:

moved netmanager binary to new bin/ directory
moved network management library to daemon/manager/network

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)