CHANGE: go debug working + seperated database and renam,ed module

Backend/database.go

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+)
+
+func OpenDatabase() (*sql.DB, error){
+	dbHost := getEnv("POSTGRES_HOST", "localhost")
+	dbName := getEnv("POSTGRES_DB", "arbeitszeitmessung")
+	dbUser := getEnv("POSTGRES_USER", "arbeit_zeit")
+	dbPassword := getEnv("POSTGRES_PASS", "password")
+
+	connStr:= fmt.Sprintf("postgres://%s:%s@%s:5432/%s?sslmode=disable", dbUser, dbPassword, dbHost, dbName)
+	return sql.Open("postgres", connStr)
+}