Add staging k8s config definition

This definition is technically already live on OKD, as we have no route and we've limited the resources. This way we can stage changes and do some integration testing. We will be doing some more development before we introduce the route + production instance. The main change we still need to introduce is #9 (closed), as well as more strict testing around completeness (like enums + more tests).

src/main/k8s/staging.yml

+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: eclipsefdn-cve-api-staging
+  namespace: foundation-internal-webdev-apps
+  labels:
+    app: eclipsefdn-cve-api
+    environment: staging
+spec:
+  selector:
+    matchLabels:
+      app: eclipsefdn-cve-api
+      environment: staging
+  replicas: 1
+  template:
+    metadata:
+      labels:
+        app: eclipsefdn-cve-api
+        environment: staging
+    spec:
+      affinity:
+        nodeAffinity:
+          preferredDuringSchedulingIgnoredDuringExecution:
+          - preference:
+              matchExpressions:
+              - key: speed
+                operator: NotIn
+                values:
+                - fast
+            weight: 1
+      containers:
+      - name: app
+        image: eclipsefdn/eclipsefdn-cve-api:latest
+        imagePullPolicy: Always
+        ports:
+        - containerPort: 8090
+        resources:
+          limits:
+            cpu: 200m
+            memory: 256Mi
+          requests:
+            cpu: 200m
+            memory: 256Mi
+        env: 
+        - name: CONFIG_SECRET_PATH
+          value: "/run/secrets/eclipsefdn-cve-api/secret.properties"
+        volumeMounts:
+        - name: secret-properties
+          mountPath: "/run/secrets/eclipsefdn-cve-api"
+          readOnly: true
+      volumes:
+      - name: secret-properties
+        secret:
+          secretName: eclipsefdn-cve-api
+---
+apiVersion: "v1"
+kind: "Service"
+metadata:
+  name: eclipsefdn-cve-api-staging
+  namespace: foundation-internal-webdev-apps
+spec:
+  ports:
+  - name: "http"
+    port: 80
+    protocol: "TCP"
+    targetPort: 8090
+  selector:
+    app: eclipsefdn-cve-api
+    environment: staging