接入极光推送一直说WifiManager.getWifiState是空

```
java.lang.NullPointerException: Attempt to invoke interface method 'int android.net.wifi.IWifiManager.getWifiEnabledState()' on a null object reference
at android.net.wifi.WifiManager.getWifiState(WifiManager.java:1506)
at android.net.wifi.WifiManager.isWifiEnabled(WifiManager.java:1518)
at cn.jiguang.g.a.t(Unknown Source)
at cn.jiguang.g.a.b(Unknown Source)
at cn.jiguang.g.a.l(Unknown Source)
at cn.jpush.android.service.PushService.runCreate(Unknown Source)
at cn.jiguang.service.d.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
at java.lang.Thread.run(Thread.java:776)