added support for line auth (#6007)

* added support for line auth

* fixed linting issues

* modified auth adapter spec to handle line auth adapter

* revert package.json changes

spec/AuthenticationAdapters.spec.js

@@ -8,6 +8,7 @@ const responses = {
   instagram: { data: { id: 'userId' } },
   janrainengage: { stat: 'ok', profile: { identifier: 'userId' } },
   janraincapture: { stat: 'ok', result: 'userId' },
+  line: { userId: 'userId' },
   vkontakte: { response: [{ id: 'userId' }] },
   google: { sub: 'userId' },
   wechat: { errcode: 0 },
@@ -29,6 +30,7 @@ describe('AuthenticationProviders', function() {
     'twitter',
     'janrainengage',
     'janraincapture',
+    'line',
     'vkontakte',
     'qq',
     'spotify',