Added Data files, among other fixes

Created ReferenceData
- files include Q42013 test file information (a very large .csv file),
and a header index table for the afore mentioned csv file, just to make
things a bit easier, per chance

utils
- StDevP now returns None when given an empty array

indivSpeedTest
- Now handles StDevP returning a None

STDs
- test for 1st line being “CPUC Tester…..” was in the wrong place

main.py
- set up example for a relative import of a data file.
- creation of StDev .csv file now adds the date time onto it