Remove watcher_tempest_plugin

In accordance with Queens global goal[1], this patch set
removes watcher tempest plugin from watcher repository since
it is stored as independent repository[2]. Jenkins job
gate-watcher-dsvm-multinode-ubuntu-xenial-nv has been modified,
it uses watcher-tempest-plugin repo now.

[1]: https://governance.openstack.org/tc/goals/queens/split-tempest-plugins.html
[2]: http://git.openstack.org/cgit/openstack/watcher-tempest-plugin/

Change-Id: I4d1207fbd73ee2519a6d40342f5fd3c5d3ee8bc7

setup.cfg

@@ -21,7 +21,6 @@ classifier =
 [files]
 packages =
     watcher
-    watcher_tempest_plugin
 data_files =
     etc/ = etc/*
 
@@ -40,9 +39,6 @@ console_scripts =
     watcher-applier = watcher.cmd.applier:main
     watcher-sync = watcher.cmd.sync:main
 
-tempest.test_plugins =
-    watcher_tests = watcher_tempest_plugin.plugin:WatcherTempestPlugin
-
 watcher.database.migration_backend =
     sqlalchemy = watcher.db.sqlalchemy.migration
 
@@ -103,7 +99,6 @@ autodoc_exclude_modules =
     watcher.db.sqlalchemy.alembic.env
     watcher.db.sqlalchemy.alembic.versions.*
     watcher.tests.*
-    watcher_tempest_plugin.*
     watcher.doc