Avoid killing create_number.py

Avoid killing create_number.py

create_numbers.py has been killed by other services as described in [1].
It's now called when ellis is up and running.

It adds few sleeps to ensure the right boot orders (signals must be send
before switching DNS).

[1] http://www.projectclearwater.org/using-start-stop-daemon-with-the-python-interpreter/

Change-Id: I87ad3828c10d3ccbc707ed8f4ab99987c6968f09
Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
(cherry picked from commit 45708eda7ba8e4ddac85930dbb5defb14b9af88b)