Install Guide: make sure that the admin can use the nova command

The first nova command example might be executed on a compute node by
the user, and it's likely that python-novaclient has not been installed
there. Suggest to the user to log on the controller or to install the
client.

Change-Id: I57009deb4a817966f9a37036f3230a418a5133e3
Partial-Bug: #1245946
backport: havana
(cherry picked from commit 24a9ad87a6356780a45f1d14bf740f4ff5ab81d7)
Install Guide: service fixes for ubuntu on neutron installation

* Open vSwitch needs a restart after the datapath module installation
* Debian/Ubuntu don't use chkconfig

Change-Id: I08519e60bcc301d49a3e3f2a33e1980f763cecdf
backport: havana
(cherry picked from commit 91aa09ecf78a827de8b02c9ead4562a63887590d)
Merge "Install Guide: make sure that the admin can use the nova command" into stable/havana