Ignore models/ and boot/ subdirs without index

Sub-directories of `models/` and `boot/` that cannot be required
(they don't have an index.js file) are silently skipped now.

This enables developers to put test files into `models/test/`.

index.js

@@ -4,6 +4,7 @@ var path = require('path');
 var _ = require('underscore');
 var loopback = require('loopback');
 var ConfigLoader = require('./lib/config-loader');
+var debug = require('debug')('loopback-boot');
 
 /**
  * Initialize an application from an options object or
@@ -287,6 +288,10 @@ function tryRequire(modulePath) {
   try {
     return require.apply(this, arguments);
   } catch(e) {
+    if(e.code === 'MODULE_NOT_FOUND') {
+      debug('Warning: cannot require %s - module not found.', modulePath);
+      return undefined;
+    }
     console.error('failed to require "%s"', modulePath);
     throw e;
   }

package.json

@@ -22,7 +22,8 @@
     "url": "https://github.com/strongloop/loopback-boot/blob/master/LICENSE"
   },
   "dependencies": {
-    "underscore": "^1.6.0"
+    "underscore": "^1.6.0",
+    "debug": "^0.8.1"
   },
   "devDependencies": {
     "loopback": "^1.5.0",

test/boot.test.js

@@ -379,6 +379,17 @@ describe('bootLoopBackApp', function() {
       boot(app, appDir);
       expect(global.fnCalled, 'exported fn was called').to.be.undefined();
     });
+
+    it('supports models/ subdirectires that are not require()able', function() {
+      givenAppInSandbox();
+      writeAppFile('models/test/model.test.js',
+        'throw new Error("should not been called");');
+
+      var app = loopback();
+      boot(app, appDir);
+
+      // no assert, the test passed when we got here
+    });
   });
 });