Add UUIDs to all tempest tests and gate check

Adds uuid4 as a decorator of the form:
@test.idempotent_id('12345678-1234-1234-1234-123456789abc')
to every test in the Tempest tree. Includes a gate check to
ensure the existence and uniqueness of the ids.

Modify check tool to ignore Tempest unit tests.

Change-Id: I19e3c7dd555a3ea09d585fb9091c357a300e6559
Co-Authored-By: Sergey Slipushenko <sslypushenko@mirantis.com>
Implements: bp test-uuid
diff --git a/tempest/api/compute/admin/test_migrations.py b/tempest/api/compute/admin/test_migrations.py
index aaf7a78..67e4fe3 100644
--- a/tempest/api/compute/admin/test_migrations.py
+++ b/tempest/api/compute/admin/test_migrations.py
@@ -29,10 +29,12 @@
         cls.client = cls.os_adm.migrations_client
 
     @test.attr(type='gate')
+    @test.idempotent_id('75c0b83d-72a0-4cf8-a153-631e83e7d53f')
     def test_list_migrations(self):
         # Admin can get the migrations list
         self.client.list_migrations()
 
+    @test.idempotent_id('1b512062-8093-438e-b47a-37d2f597cd64')
     @testtools.skipUnless(CONF.compute_feature_enabled.resize,
                           'Resize not available.')
     @test.attr(type='gate')