Added logo for Gentoo Linux
Merge pull request #179 from f0o/gentoo-logo

Added logo for Gentoo Linux

Attribution statement:
I acknowledge that the "g" logo is a trademark of Gentoo Foundation, Inc., that it is copyright Gentoo Foundation, Inc, and that it is used only to refer to systems that identify as pertaining to "the Gentoo project".  LibreNMS is not part of the Gentoo project and is not directed or managed by Gentoo Foundation, Inc.