Coursera-GettingCleaningDataProject

1. Download the dataset from th url provided if it does not already exist in the working directory.
2. Read both the train and test datasets and merge them into x(measurements), y(activity) and subject.
3. Load the data for feature, activity info and extract columns named 'mean'(-mean) and 'standard'(-std).
4. Extract data by selected columns(, and merge x, y(activity) and subject data..
5. Generate 'Tidy Dataset' with write.table() as .txt file in the directory. The result is shown in the file tidy_dataset.txt.