Fix linux detection

[ferferga]

Linux wasn't detected correctly in my Raspberry Pi device as the returned string in OSTYPE is linux-gnueabihf instead of linux-gnu

Removed also the author block as I saw that there are other contributions from other people throughout the commit history, so the authors of the code are not only you but also @Incrementing and @VarunBatraIT. People looking for the full history of contributions can directly check in https://github.com/zevilz/zImageOptimizer/graphs/contributors

[ferferga]

Hello @zevilz

Any news about this?

[VarunBatraIT]

I wouldn't mind his signature on Author name. He is already taking full responsibility for this repository. At least my contribution was not a lot nor I think I am an expert in answering any questions regarding this repository. Next, Linux detection codes look good to me.