First raw version of a simulation model

src/libs/models/simulation.js

+const mongoose = require('mongoose');
+const libs = `${process.cwd()}/libs`;
+const log = require(`${libs}/log`)(module);
+const Schema = mongoose.Schema;
+
+// set up a mongoose model
+var SimulationSchema = new Schema({
+    location: {
+        type: Number,
+        required: true
+    },
+    time: {
+        type: Number,
+        required: true
+    }
+});