Reconfigure Neutron to use only one network type

When network type isn't selected during network creation (for example, using
Horizon), the first network type from the Neutron plugin config file seems to
be selected. Currently it's 'local' and it leads to wrong network type creation

Change-Id: I514af033bf5fff380e252aaef8e020ca2edaf993
Closes-bug: #1352203
Merge "Reconfigure Neutron to use only one network type"