NgnConfigurationEntry.QOS_SIP_CALLS_TIMEOUT does not work in NgnAVSession.java

```
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What steps will reproduce the problem?
1.check the log via log cat
2.
3.

What is the expected output? What do you see instead?
In ScreenQoS.java, NgnConfigurationEntry.QOS_SIP_CALLS_TIMEOUT config-item is
get/set as String.
But in NgnAVSession.java it is accessed via mConfigurationService.getInt().
This will throw Exception.
Suggest to refine ScreenQoS.java as below:
long timeout = NgnConfigurationEntry.DEFAULT_QOS_SIP_CALLS_TIMEOUT;

String timeoutStr = mConfigurationService.getString( NgnConfigurationEntry.QOS_SIP_CALLS_TIMEOUT, String.valueOf(NgnConfigurationEntry.DEFAULT_QOS_SIP_CALLS_TIMEOUT));
try {
timeout = Long.valueOf(timeoutStr).longValue();
} catch(Throwable ex) {
ex.printStackTrace();
}
mSession.setSessionTimer(timeout,
mConfigurationService.getString(NgnConfigurationEntry.QOS_REFRESHER,
NgnConfigurationEntry.DEFAULT_QOS_REFRESHER));

What version of the product are you using? On what operating system?

Please provide any additional information below.

```

Original issue reported on code.google.com by `gumin...@gmail.com` on 21 Aug 2013 at 1:25