Change network names in Fuel to match with Openstack docs

There is mismatch between how the OpenStack networks are named in OpenStack documentation and in Fuel UI/docs.

To match better with OpenStack docs I propose the following changes:

1. Admin network. Leave as is. There is no similar network in OpenStack

2. Public network. Rename to "External". OpenStack documentation always refers this network as External.

3. Floating. Rename to Floating IP Range. Currently Floating IP Range is subset of IP addresses from External network.

4. Management network. Leave as is.

5. Storage network. I propose leave it as is. OpenStack documentation refers to Data network, but Storage network better describes its purpose. Mirantis OpenStack actually have several Data networks - Storage is one of them.

6. VM Networks (Fixed). Leave as is, since this network is not OpenStack network but exists inside OpenStack installation and represents CIDR range, used to contain tenant virtual networks. Exists in Nova-Network only. It is a kind of Data network.

7. Private. Rename to VM Networks (Private). It is the same network range as described in #6, but exists in Neutron only. Unlike VM Networks (Fixed), this range has no simple access by IP address possible from host OpenStack nodes, at least without special manually created bridge in Neutron. It is also a kind of Data network.