Updated nova-network to correct info given

Changed intro text, and final step, as per bug report. Slightly updated
wording and corrected bug number.

Change-Id: I91fa36d6bb1c4713f8d776e5ca71454c839f91e2
backport: havana
Closes-Bug: #1245960
Added instructions for deleting default mysql db to other services

Copied instructions from glance, added to keystone, nova, and heat. Did not
add to neutron, as the chapter layout is significantly different.

Change-Id: If347859a1a38a1353395e4fec58c9f199a72a4eb
backport: havana
Closes-Bug: #1248599
Merge "Added instructions for deleting default mysql db to other services"
Merge "Updated nova-network to correct info given"