Hide percentage output in kekatar when using pipes

This works well:
`tar -cf - folder1 | /Volumes/Keka/Keka.app/Contents/Resources/keka7z a -si -txz folder1.txz`

But I discovered that this results in a corrupt file:
`/Volumes/Keka/Keka.app/Contents/Resources/kekatar -cf - folder1 | /Volumes/Keka/Keka.app/Contents/Resources/keka7z a -si -txz folder1.txz`

The only difference there is that **kekatar** was used instead of the standard **tar** binary (the one included with macOS Sierra).

When I discovered this, I tested it with a small text file and piped the output from **kekatar** to **dd** to save it as a text file, so I could see what's going on there...

Compared to the output from standard **tar**, it seems that **kekatar** was adding "_KEKA_PROGRESS_6" to the file for some reason, so that's why piping the output from **kekatar** to **keka7z** resulted in a corrupt .txz file that even Keka refused to open.