Add ability give name to Pushmanager

This patch adds ability to give name to push managers and their connections; this is very handy when java app utilizes more than one push manager at the same time and something goes wrong (push certificate expires for example).

```
[2014/05/07 10:01:42.705] APNS-EventLoop-3 ERROR [c.r.p.a.PushManager]: [apns/o7gtoyballsipad] Connection failed: ApnsConnection [name=apns/myapp connection-1]: Received fatal alert: certificate_expired
javax.net.ssl.SSLException: Received fatal alert: certificate_expired
        at sun.security.ssl.Alerts.getSSLException(Alerts.java:208) ~[na:1.7.0_55]
        at sun.security.ssl.SSLEngineImpl.fatal(SSLEngineImpl.java:1619) ~[na:1.7.0_55]
        at sun.security.ssl.SSLEngineImpl.fatal(SSLEngineImpl.java:1587) ~[na:1.7.0_55]
        at sun.security.ssl.SSLEngineImpl.recvAlert(SSLEngineImpl.java:1756) ~[na:1.7.0_55]
        at sun.security.ssl.SSLEngineImpl.readRecord(SSLEngineImpl.java:1060) ~[na:1.7.0_55]
        at sun.security.ssl.SSLEngineImpl.readNetRecord(SSLEngineImpl.java:884) ~[na:1.7.0_55]
```

Errors and warnings in push manager and apnsconnections are also no longer logged as DEBUG, because connection errors should be logged as warn/err.