Create API to update openrc

Create API to update openrc

API: /api/v1/functest/openstack/action
METHOD: POST
PARAMS:
{
    "action": "update_openrc",
    "args": {
         "openrc": {
             "OS_AUTH_URL": "http://192.168.30.222:5000/v3",
             "OS_IDENTITY_API_VERSION": "3",
             "OS_IMAGE_API_VERSION": "2",
             "OS_PASSWORD": "console",
             "OS_PROJECT_DOMAIN_NAME": "default",
             "OS_PROJECT_NAME": "admin",
             "OS_TENANT_NAME": "admin",
             "OS_USERNAME": "admin",
             "OS_USER_DOMAIN_NAME": "default"
         }
    }
}

JIRA: FUNCTEST-855

Change-Id: I7c935483c264f2b1b47239684392c8a37dc23d26
Signed-off-by: Linda Wang <wangwulin@huawei.com>