Update logger via logging.getLogger()

Update logger via logging.getLogger()

1. The module functest.utils.functest_logger has been deleted and
   logger has been reconfigured in functest [1].
2. Update all related modules to get loggers via logging.getLogger().

[1] https://gerrit.opnfv.org/gerrit/#/c/34019/

JIRA: FUNCTEST-824

Change-Id: I89f5d15342b5f257fbc2700655e255a4e28bd36f
Signed-off-by: Linda Wang <wangwulin@huawei.com>