Removed references to unused  libvirt_ovs_bridge flag.

The libvirt_ovs_bridge flag was unused in the code and removed under bug
1251813. This update removes it from the configuration mapping and the
current output (I didn't want to regenerate the entire configuration
tables this early in the cycle to avoid impacting backports too badly).

Change-Id: I91f6e58a7190279447a0f9439f7e30d662e7befd
Closes-Bug: #1251813
Added missing python-novaclient installation

The instructions for Debian/Ubuntu were missing python-novaclient
installation, required to complete the procedure.

Change-Id: Ic64627f1ebec3d2093da1c3e522a15c2638a4465
backport: havana
Closes-Bug: #1252604
Merge "Added missing python-novaclient installation"
Merge "Removed references to unused  libvirt_ovs_bridge flag."