Increasing HeaderBufferSize on AzkabanExecutorServer

No of total flows in running and preparing state increase leads to increase in headerbuffer size(by get api call of Line 703 of ExecutorManager.java) 

and there by leading to FULL HEAD (httpclient. Response Exception) as it exceeding 4k which is default value 
and there by throwing IOException from handleAjaxUpdateRequest of ExecutorServlet and there by all flows in preparing state are getting Evicted. (Evicting flow " + flow.getExecutionId() + ". The executor is unresponsive. Line 854 of ExecutorManager.java).
Please remove `_KB` from all the field names.  These values are in _bytes_, not kilobytes.