ROOT

1. Download the last version of Towelroot from HERE (click on λ symbol to get it)
2. Copy tr.apk into internal memory of your phone and install it with a File Manager
3. Open Towelroot and tap on "make it ra1n"
4. Now simply install SuperSU by Chainfire from Play Store
5. Open SuperSU. It will ask to update the SU binary: tap on "Continue", then on "Normal"
6. Reboot
7. Done! 
8. You can uninstall Towelroot app, if you want or need