Added HashMap definition.

hashmap/hashmap-tests.ts

@@ -0,0 +1,24 @@
+/// <reference path="hashmap.d.ts"/>
+
+var map : HashMap<string, number> = new HashMap<string, number>();
+
+map.set("foo", 123);
+
+var value : number = map.get("foo");
+
+map.has("foo");
+
+map.remove("foo");
+
+var keys : string[] = map.keys();
+
+var values : number[] = map.values();
+
+var count : number = map.count();
+
+map.forEach(function(value : number, key : string) : void {
+        console.log(key);
+        console.log(value);
+});
+
+map.clear();