Added the runner class

ref #11

src/models/Runner.ts

@@ -0,0 +1,18 @@
+import { Entity, Column } from "typeorm";
+import { IsNotEmpty,} from "class-validator";
+import { Participant } from "./Participant";
+import { RunnerGroup } from "./RunnerGroup";
+
+/**
+ * Defines a runner.
+*/
+@Entity()
+export class Track extends Participant {
+  /**
+   * The runner's associated group.
+   */
+  @Column()
+  @IsNotEmpty()
+  //TODO:Relation
+  group: RunnerGroup;
+}