[2/2] Settings : Upgrade network traffic meter

*Updated class name to be less ambiguous
*Replaced the multi-check in settings with a proper listview
*Added the ability to view up-stream, down-stream or both
*Added the option to change how often it refreshes
*Added a check before it updates the status bar to prevent it from refreshing e$
*Added icons to show data direction
*Remove unused style attributes
*Stylish status bar font

Icon artwork is courtesy android design downloads
Some features were inspired by previous work done by 0xD34D

Change-Id: I91ac2794aa05e4675dba257451e3ec0a1ec13166