Create floating ip by normal user

In real use case, it should be the end user who will create floating
ip and associate with loadbalancer vip.

Also use config_drive when creating backend server, to keep consistent
with amphora creation in octavia itself.

Tested in devstack.

Change-Id: I2cbee37f494a5775a96f8c285f0e52c0b2550d5b
3 files changed