Create run_analysis.R

This script does the following:
1) Merges the training and the test sets to create one data set. 
2) Extracts only the measurements on the mean and standard deviation for each measurement. 
3) Uses descriptive activity names to name the activities in the data set 
4) Appropriately labels the data set with descriptive variable names. 
5) Calls a second script call run_analysis_tidy_data2.R to complete the task of creating
## a separate independent dataset starting from the original raw data.