Express.Router definition

Added the IRouter and Router definitions. It compiles just fine with 0.9.5.0 but npm install gives me:

```
=============================================================================
                    Errors in files 
=============================================================================
----------------- For file:express/express.d.ts
...d.ts/DefinitelyTyped/express/express.d.ts(65,37): error TS2173: Generic type references must include all type arguments.

=============================================================================
----------------- For file:express/express-tests.ts
...d.ts/DefinitelyTyped/express/express.d.ts(65,37): error TS2173: Generic type references must include all type arguments.

----------------- For file:supertest/supertest-tests.ts
...d.ts/DefinitelyTyped/express/express.d.ts(65,37): error TS2173: Generic type references must include all type arguments.
=============================================================================
```