NPE in ConfigurationProviderHTTP needs to be handled.

NPE in ConfigurationProviderHTTP needs to be handled.
This is seen at quite a lot of places.

Please refer to the integration test results at :

https://docs.google.com/a/globallogic.com/spreadsheet/ccc?key=0AmLvaJ8oRZ-TdHJBNHJ0eGZfbjBaenBSVGM2VS1oNlE#gid=0


Stack Trace :

SDKD: Mar 12, 2013 1:55:39 AM com.couchbase.client.CouchbaseConnectionFactory$Resubscriber run
SDKD: WARNING: Resubscribe attempt failed:
SDKD: java.lang.NullPointerException
SDKD: at com.couchbase.client.vbucket.ConfigurationProviderHTTP.getBucketConfiguration(ConfigurationProviderHTTP.java:149)
SDKD: at com.couchbase.client.vbucket.ConfigurationProviderHTTP.subscribe(ConfigurationProviderHTTP.java:319)
SDKD: at com.couchbase.client.CouchbaseConnectionFactory$Resubscriber.run(CouchbaseConnectionFactory.java:405)
SDKD: at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
SDKD: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
SDKD: at java.lang.Thread.run(Thread.java:619)
SDKD: Mar 12, 2013 1:55:39 AM com.couchbase.client.CouchbaseConnectionFactory$Resubscriber run