add campagin service

src/myaktion/service/campaign.go

+package service
+
+import (
+	"log"
+
+	model "gitlab.reutlingen-university.de/petrinov/myaktion-go/Model"
+)
+
+var (
+	campaginStore map[uint]*model.Campaign
+	actCampaignId = 1
+)
+
+func init() {
+	campaginStore = make(map[uint]*model.Campaign)
+}
+
+func CreateCampagin(campaign *model.Campaign) error {
+	campaign.ID = uint(actCampaignId)
+	campaginStore[uint(actCampaignId)] = campaign
+
+	actCampaignId += 1
+
+	log.Printf("Successfully stored new campaign with ID %v in database.", campaign.ID)
+	log.Printf("Stored: %v", campaign)
+	return nil
+
+}