Add binary search tree.

src/data-structures/tree/binary-search-tree/BinarySearchTree.js

@@ -0,0 +1,19 @@
+import BinarySearchTreeNode from './BinarySearchTreeNode';
+
+export default class BinarySearchTree {
+  constructor() {
+    this.root = new BinarySearchTreeNode();
+  }
+
+  insert(value) {
+    this.root.insert(value);
+  }
+
+  contains(value) {
+    return this.root.contains(value);
+  }
+
+  toString() {
+    this.root.toString();
+  }
+}