Support laravel 5.1

Fix tests.

Fix tests.

Fix docblocks. (overtrue#69)

Merge.

Add User::getProviderName()

Add username.

No guzzle exception, resolve#58

Merge branch 'master' of github.com:overtrue/socialite

Get token from EasyWeChat AccessToken class. (overtrue#53)

* Get token from EasyWeChat AccessToken class.

* StyleCI.