Cleanup approval requirement testing

On further inspection, trigger requirements will still be required
for parts of the kind of pipeline construction that we are using in
OpenStack; the idea that they could be completely replaced by
pipeline requirements is incorrect.  To that end, un-deprecate
trigger requirements and cleanup the testing of both of them so that
each requirement is tested (relatively) independently.  A small
amount of requirement composition is also tested, though all possible
combinations (a lot!) are not.

Move this testing into a new file for organizational purposes.

Also, support multiple vote values (eg, "+1" or "+2") when requiring
an approval.

Change-Id: I683c9a574ced0e27ced59e62b8059fef2dfd8b20
diff --git a/tests/fixtures/layout-requirement-older-than.yaml b/tests/fixtures/layout-requirement-older-than.yaml
new file mode 100644
index 0000000..2edf9df
--- /dev/null
+++ b/tests/fixtures/layout-requirement-older-than.yaml
@@ -0,0 +1,39 @@
+pipelines:
+  - name: pipeline
+    manager: IndependentPipelineManager
+    require:
+      approval:
+        - username: jenkins
+          older-than: 48h
+    trigger:
+      gerrit:
+        - event: comment-added
+    success:
+      gerrit:
+        verified: 1
+    failure:
+      gerrit:
+        verified: -1
+
+  - name: trigger
+    manager: IndependentPipelineManager
+    trigger:
+      gerrit:
+        - event: comment-added
+          require-approval:
+            - username: jenkins
+              older-than: 48h
+    success:
+      gerrit:
+        verified: 1
+    failure:
+      gerrit:
+        verified: -1
+
+projects:
+  - name: org/project1
+    pipeline:
+      - project1-pipeline
+  - name: org/project2
+    trigger:
+      - project2-trigger