Lowercase OVS sample config section headers

The "Sample Configurations" section of ovs_neutron_plugin.ini
has uppercased section headers.  In Havana the section headers
were normalized to lowercase, but the sample configs were never
updated.

Change-Id: Ic33392788317adcd6eb86caeef4f25aa4a3d10c8
Closes-Bug: #1279418
Merge "Lowercase OVS sample config section headers"