dovetail tool: remove installer and CI related variables

dovetail tool: remove installer and CI related variables

JIRA: DOVETAIL-371

1. remove all the envs in functest_config.yml and yardstick_config.yml
2. remove all relative cmds in cmd_config.yml
3. remove all the envs when running a new functest/yardstick container
4. add some variables just for functest pushing results to db
5. get the external network name for yardstick
6. make --debug/-d just control the log level shown on the screen
7. set requests=2.10.0 since python-openstackclient needs
   'requests!=2.12.2,!=2.13.0,>=2.10.0'

Change-Id: I9f941e09d067fc95a14c3c9be1374f41df4a9a16
Signed-off-by: xudan <xudan16@huawei.com>