client.tests: small fix for cpuflags

fixs:
    1. fix module import error
    2. correct src dir

Signed-off-by: Xu Tian <xutian@redhat.com>
Merge pull request #28 from xutian/fix_cpuflags_test

client.tests: small fix for cpuflags
cgroup_test: Check libcgroup-tool and environment before starting test

Signed-off-by: Li Yang <liyang.fnst@cn.fujitsu.com>