The goal is to prepare tidy data that can be used for later analysis.

run_analysis.R
Merges the training and the test sets to create one data set.
Extracts only the measurements on the mean and standard deviation for
each measurement.
Uses descriptive activity names to name the activities in the data set
Appropriately labels the data set with descriptive variable names.
Creates a second, independent tidy data set with the average of each
variable for each activity and each subject.