Skip tests if cinder is not installed

The test_capacity_filter_passes_infinite and test_capacity_filter_passes_unknown
tests were failing when cinder is not installed. Skip the tests like the other
tests for test_host_filters.

Change-Id: I5ebfa2dca05b6e89a12e3153598bf4699da888de
Signed-off-by: Chuck Short <chuck.short@canonical.com>
Fixes 'not in' operator usage

Change-Id: Id4c83e32f6dcb4f710c5a8d8b6f130038cf07648
Merge "Fixes 'not in' operator usage"
Merge "Skip tests if cinder is not installed"