Create run_analysis.R

This is the Assessments for Coursera of Getting and Cleaning Data start on 2014-6-2. If there is data under directory "UCI HAR Dataset" with  https://d396qusza40orc.cloudfront.net/getdata%2Fprojectfiles%2FUCI%20HAR%20Dataset.zip . It will generate "Mean_STD_merge.txt" and "group_average_merge.txt" for the purpose of https://class.coursera.org/getdata-004/human_grading/view/courses/972137/assessments/3/submissions .