Avoid "bulk-comparing" pod resources during sync. (#109)

* Avoid "bulk-comparing" pod resources during sync.

First attempt to fix bogus restarts due to the reported mismatch
of container resources where one of the resources is an empty struct,
while the other has all fields set to nil.

In addition, add an ability to set limits and requests per pod, as well as the operator-level defaults.

manifests/testpostgresql.yaml

@@ -23,8 +23,12 @@ spec:
       max_connections: "10"
       log_statement: "all"
   resources:
-    cpu: 10m
-    memory: 100Mi
+    requests:
+      cpu: 10m
+      memory: 100Mi
+    limits:
+      cpu: 300m
+      memory: 3000Mi
   patroni:
     initdb:
       encoding: "UTF8"