Second beta

Changelog:

• Fixed HR sensor bug
• Optimized some code

Bugs:

• Still FC with "Cannot add a null child view to a ViewGroup" error
• If you find any, open an issue with logcat

First beta

Bugs:

• Some crashes with "Cannot add a null child view to a ViewGroup" error (Sometimes work sometimes FC)
• HR sensor keeps tracking HR when timer finished, reboot to avoid battery drain
• If you find any, open an issue with logcat