Add export to ts interfaces (#72)

* Add export to ts interfaces

* fix test

* fix lint

Author: pierre-H

src/generators/TypescriptInterfaceGenerator.test.js

@@ -50,7 +50,7 @@ test("Generate a typescript interface", () => {
 
   expect(fs.existsSync(tmpobj.name + "/interfaces/foo.ts")).toBe(true);
 
-  const res = `interface Foo {
+  const res = `export interface Foo {
   '@id'?: string;
   id: string;
   foo: any;

templates/typescript/interface.ts

@@ -1,4 +1,4 @@
-interface {{ name }} {
+export interface {{ name }} {
   '@id'?: string;
   id: string;
 {{#each fields}}