Save fuel_version field for plugins model

It's important to keep all of the information
which plugin provides about dependencies.
In the future versions there might be cases
when we have to write some workaround not to
brake old plugins.

Change-Id: Id0f45def2972a60040e3a1d2a016a1ed46a05ed3
Implements: blueprint cinder-neutron-plugins-in-fuel
Merge "Save fuel_version field for plugins model"