Wolfplex logo refresh

Summary:
New version of the Wolfplex logo without the circle N symbol + extended version for a phabricator use.

Fixes T12.

Test Plan: Checked again the logo in firefox-38.0.5-1.

Reviewers: dereckson

Subscribers: Kaliiixx

Projects: GFX

Maniphest Tasks: T12

Differential Revision: https://phabricator.wolfplex.be/D1