Fix gate job of Senlin functional test

This patch tries to fix gate job of Senlin functional test. Three
works were done:
 - Adding a judgement in plugin.sh to skip python-senlinclient
   installation when this is an installation happens in gate side;
 - Revising tox.ini to pass necessary environment variables for
   functional test;
 - Adding exetuable permission to post_test_hook.sh;

Partially implement: blueprint functional-test-startpoint
Change-Id: I36508910a50299afa388864704fbcbdbee609dec

devstack/plugin.sh

@@ -12,7 +12,12 @@ if is_service_enabled sl-api sl-eng; then
     if [[ "$1" == "stack" && "$2" == "install" ]]; then
         echo_summary "Installing senlin"
         install_senlin
-        install_senlinclient
+        if [[ "$ERROR_ON_CLONE" == "True" ]]; then
+            echo_summary "This is a gate job, skip senlinclient installation"
+        else
+            echo_summary "Installing senlinclient"
+            install_senlinclient
+        fi
         cleanup_senlin
     elif [[ "$1" == "stack" && "$2" == "post-config" ]]; then
         echo_summary "Configuring senlin"

tox.ini

@@ -20,6 +20,7 @@ commands =
 whitelist_externals = bash
 
 [testenv:functional]
+passenv = OS_USERNAME OS_PASSWORD OS_TENANT_NAME OS_USER_DOMAIN_NAME OS_PROJECT_DOMAIN_NAME OS_REGION_NAME OS_AUTH_URL
 commands =
     ostestr --slowest --concurrency 1 --regex '^(.*?tests\.functional)' {posargs}