helpers.sh: 	added function findCSVColumnPostion
		added Three statistic functions: mean, stdev and median
jmeter-ec2.sh: 	added new flag cfgCalculateSimpleStatsFromAResultFile that allows to calculate some basic statistics for latency, response time and response size
		added min and max values for all 3 metrics: latency, resptime, respsize
		refactored code to use findCSVColumnPostion to handle result files with different column setting