use /-/whoami endpoint instead of /whoami

Allows to get rid of referer magic, so it's a nice change to have.

See this issue for details:
https://github.com/npm/npm-registry-client/issues/88

lib/index-api.js

@@ -41,6 +41,9 @@ module.exports = function(config, auth, storage) {
       next('route')
     }
   })
+  app.get('/-/whoami', function(req, res, next) {
+    next({ username: req.remote_user.name })
+  })
 
   // TODO: anonymous user?
   app.get('/:package/:version?', can('access'), function(req, res, next) {

test/functional/basic.js

@@ -129,5 +129,13 @@ module.exports = function() {
       cb()
     })
   })
+
+  it('who am I?', function(cb) {
+    server.request({uri:'/-/whoami'}, function(err, res, body) {
+      assert.equal(res.statusCode, 200)
+      assert.equal(body.username, 'test')
+      cb()
+    })
+  })
 }