[beeswax] Filter out sessions with empty guid or secret key

When secret or guid in beeswax_session is '' and you run a query form Hive, you get this error in the logs.

16/Mar/2016 13:14:17 +0000] thrift_util DEBUG Thrift call <class 'TCLIService.TCLIService.Client'>.ExecuteStatement returned in 6ms: TExecuteStatementResp(status=TStatus(errorCode=None, errorMessage=None, sqlState=None, infoMessages=['*java.nio.BufferUnderflowException:null:16:15', 'java.nio.Buffer:nextGetIndex:Buffer.java:498', 'java.nio.HeapByteBuffer:getLong:HeapByteBuffer.java:406', 'org.apache.hive.service.cli.HandleIdentifier:<init>:HandleIdentifier.java:46', 'org.apache.hive.service.cli.Handle:<init>:Handle.java:38', 'org.apache.hive.service.cli.SessionHandle:<init>:SessionHandle.java:45', 'org.apache.hive.service.cli.SessionHandle:<init>:SessionHandle.java:41', 'org.apache.hive.service.cli.thrift.ThriftCLIService:ExecuteStatement:ThriftCLIService.java:505', 'org.apache.hive.service.cli.thrift.TCLIService$Processor$ExecuteStatement:getResult:TCLIService.java:1313', 'org.apache.hive.service.cli.thrift.TCLIService$Processor$ExecuteStatement:getResult:TCLIService.java:1298', 'org.apache.thrift.ProcessFunction:process:ProcessFunction.java:39', 'org.apache.thrift.TBaseProcessor:process:TBaseProcessor.java:39', 'or...
[16/Mar/2016 13:14:17 +0000] conf ERROR The application won't work without a running HiveServer2.
Traceback (most recent call last):
File "/opt/cloudera/parcels/CDH-5.5.1-1.cdh5.5.1.p0.11/lib/hue/apps/beeswax/src/beeswax/conf.py", line 185, in config_validator
server.get_databases()
File "/opt/cloudera/parcels/CDH-5.5.1-1.cdh5.5.1.p0.11/lib/hue/apps/beeswax/src/beeswax/server/dbms.py", line 151, in get_databases
handle = self.execute_and_wait(query, timeout_sec=timeout)
File "/opt/cloudera/parcels/CDH-5.5.1-1.cdh5.5.1.p0.11/lib/hue/apps/beeswax/src/beeswax/server/dbms.py", line 548, in execute_and_wait
handle = self.client.query(query)
File "/opt/cloudera/parcels/CDH-5.5.1-1.cdh5.5.1.p0.11/lib/hue/apps/beeswax/src/beeswax/server/hive_server2_lib.py", line 930, in query
return self._client.execute_async_query(query, statement)
File "/opt/cloudera/parcels/CDH-5.5.1-1.cdh5.5.1.p0.11/lib/hue/apps/beeswax/src/beeswax/server/hive_server2_lib.py", line 703, in execute_async_query
return self.execute_async_statement(statement=query_statement, confOverlay=configuration)
File "/opt/cloudera/parcels/CDH-5.5.1-1.cdh5.5.1.p0.11/lib/hue/apps/beeswax/src/beeswax/server/hive_server2_lib.py", line 727, in execute_async_statement
res = self.call(self._client.ExecuteStatement, req)
File "/opt/cloudera/parcels/CDH-5.5.1-1.cdh5.5.1.p0.11/lib/hue/apps/beeswax/src/beeswax/server/hive_server2_lib.py", line 597, in call
raise QueryServerException(Exception('Bad status for request %s:\n%s' % (req, res)), message=message)
QueryServerException: Bad status for request TExecuteStatementReq(confOverlay={}, sessionHandle=TSessionHandle(sessionId=THandleIdentifier(secret='', guid='')), runAsync=True, statement="SHOW DATABASES LIKE '*'"):