Add a folder to store experiments removing frequencies from KuHar and MotionSense

[alvespatrick]

I added a folder (for better organization) to store experiments that remove high frequencies and compare the performance of RF, SVM and KNN classifiers.

The idea was to evaluate if with low frequencies we can get a good performance.

I've already added the experiments for resampled datasets at 50 Hz, 30 Hz, and 20 Hz from both datasets.

[alvespatrick]

I found some bugs in the function remove_high_frequencies.