Fixed issue regarding connecting to a non-existent bucket

Connecting to a Membase server correctly, but specifying a
bucket that doesn't exist causes the BufferedReader in the
readToString function to be null. This causes a NPE when we
attempt to close the reader.

Change-Id: I7f82596156c697b57b061bf066686aded16b772a
Reviewed-on: http://review.couchbase.org/7575
Tested-by: Matt Ingenthron <[email protected]>
Reviewed-by: Matt Ingenthron <[email protected]>

Author: Mike Wiederhold

src/main/java/net/spy/memcached/vbucket/ConfigurationProviderHTTP.java

@@ -266,7 +266,9 @@ private String readToString(URLConnection connection) throws IOException {
 		}
 		return buffer.toString();
 	    } finally {
-	    reader.close();
+	    	if (reader != null) {
+	    		reader.close();
+	    	}
 	}
     }