Replace Kubernetes YAML sed-replacements by Kustomize

Closes #17 (closed)

Change infrastructure of Kubernetes files for the uc applications and workload generators. The new structure is:
--uc-application
---- base
---- overlay
-------uc1-application
-------uc2-application

Also use Kustomize for building the files for deployment

execution/uc1-workload-generator/deployment.yaml

@@ -21,7 +21,7 @@ spec:
         - name: KAFKA_BOOTSTRAP_SERVERS
           value: "my-confluent-cp-kafka:9092"
         - name: NUM_SENSORS
-          value: 25000
+          value: "25000"
         - name: POD_NAME
           valueFrom:
             fieldRef: