Final Version

Create a dataframe with mean() values across observation windows from
smartphone data.

1] Davide Anguita, Alessandro Ghio, Luca Oneto, Xavier Parra and Jorge
L. Reyes-Ortiz. Human Activity Recognition on Smartphones using a
Multiclass Hardware-Friendly Support Vector Machine. International
Workshop of Ambient Assisted Living (IWAAL 2012). Vitoria-Gasteiz,
Spain. Dec 2012