Currently FloatingIPPollster is using Nova client to get floating
IP metrics instead of accessing OpenStack DB directly. So there are
some attributes can't be accessed from Nova /os-floating-ips REST API.
In this fix, those attributes usage will be removed temporarily.
And they will be back after fix the Nova bug 1174802.
Fixes bug 1173845
Change-Id: I61572c50db6f90c26bbdb7da5f0e9a249b405e58