Problem: if a user issue the cmd 'openstack floating ip create public'
and has already maxed his quota for FIP, OSC exits with a not so useful
message:

>jordan@jordan-XPS13-9333:~ $ openstack floating ip create public
>HttpException: Conflict

This patches catch the HttpException earlier and prints a more
verbose message:

> jordan@jordan-XPS13-9333:~ $ openstack floating ip create public
> Error while executing command: Quota exceeded for resources: ['floatingip']

Change-Id: I7c87524d871d230d92f007c32e06439b34c7194a

this will better isolate the unit tests from the functional tests.
unfortunately, the "integration" tests had to be lumped into the
"unit" tests since we need the separation in testr.conf

Change-Id: Ifd12198c1f90e4e3c951c73bfa1884ab300d8ded