Update SDK tools to version 24.0.0

Update SDK tools version to 24
Update SDK tools checksum (using sha256sum)
Remove workaround to update tools using previous version.

This update fixes all the issues about SDK tools version 23.0.5 required by Android Lollipop and new updates.

Google released a new version of SDK tools, further information here:
https://developer.android.com/sdk/index.html#Other

Download:
http://dl.google.com/android/android-sdk_r24-linux.tgz