Allow hiding percentage for CPU and RAM

[cshaa]

I have no idea what I'm doing but it seems to have worked 🎉
Closes #35.

[cshaa]

@PlugaruT Bump! Any opinion on the PR? I've been using it for a month on my machine and it works like a charm!

[PlugaruT]

Thanks for your contribution @m93a
I am going to try it out on my machine.
In the last period I don't have enough time to work on this and I almost stopped using eOS.
That's the main reason I haven't been active on this repo.