Check encode time for mandatory resolutions.

Currently it there is no criteria for failing or passing depending on the encode time. It will print out the average, max and min, also an error message will be printed out as reportInfo (do not want to fail the test) when no stats can be gathered. 

Since I do know any acceptable encode time value ranges I think this is sufficient for now.
I guess for now I can leave them as single functions in util.js until encapsulation in a class is necessary.