Consume horizon master

Previously the repository consumes horizon from amotoki's
private github repository for initial testing.
Let's switch it to the main horizon repository.

To test this, local.conf needs to be something like below:
(Patch set number may need to be changed.)
-----
enable_plugin neutron-vpnaas https://git.openstack.org/openstack/neutron-vpnaas
enable_plugin neutron-vpnaas-dashboard https://git.openstack.org/openstack/neutron-vpnaas-dashboard refs/changes/05/476005/6
-----

Implement blueprint split-out-neutron-xaas-dashboards
Depends-On: Ib304ddef381d80011f7030fdd5049aab0e901ae6
Change-Id: I11a927ae799102def257edc5c18486acd3700299

devstack/plugin.sh

@@ -10,6 +10,12 @@ function install_neutron_vpnaas_dashboard {
 
 function configure_neutron_vpnaas_dashboard {
     cp -a $VPNAAS_ENABLED_DIR/_[0-9]*.py $HORIZON_ENABLED_DIR
+    # The following is to make vpnaas dashboard work with
+    # the master horizon with neutron vpnaas support.
+    # At now it seems overriding enabled file does not work.
+    # (horizon bug 1700325)
+    rm -f $DEST/horizon/openstack_dashboard/enabled/_1470_project_vpn_panel.py
+    rm -f $DEST/horizon/openstack_dashboard/enabled/__pycache__/_1470_project_vpn_panel.*
     # NOTE: If locale directory does not exist, compilemessages will fail,
     # so check for an existence of locale directory is required.
     if [ -d $VPNAAS_DASHBOARD_DIR/neutron_vpnaas_dashboard/locale ]; then

tools/tox_install.sh

@@ -16,8 +16,7 @@ function pip_install() {
 # and honour any/all Depends-On headers in the commit message
 function install_from_git() {
     ZUUL_CLONER=/usr/zuul-env/bin/zuul-cloner
-    # GIT_HOST=git.openstack.org
-    GIT_HOST=github.com
+    GIT_HOST=git.openstack.org
     PROJ=$1
     EGG=$2
 

tox.ini

@@ -7,8 +7,7 @@ skipsdist = True
 usedevelop = True
 install_command = {toxinidir}/tools/tox_install.sh {env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 setenv = VIRTUAL_ENV={envdir}
-         # BRANCH_NAME=master
-         BRANCH_NAME=drop-vpnaas
+         BRANCH_NAME=master
          CLIENT_NAME=neutron-vpnaas-dashboard
          NOSE_WITH_OPENSTACK=1
          NOSE_OPENSTACK_COLOR=1
@@ -17,8 +16,7 @@ setenv = VIRTUAL_ENV={envdir}
          NOSE_OPENSTACK_SHOW_ELAPSED=1
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
-       os:amotoki/horizon:horizon
-       # os:openstack/horizon:horizon
+       os:openstack/horizon:horizon
 commands = {[unit_tests]commands}
 
 [unit_tests]