7-Eleven Inc. is celebrating people coming together by offering a free, small Slurpee drink on “Purple Friday” – Nov. 26. 7-Eleven wants to extend the fun of its Slurpee Unity Tour that visited 14 cities before arriving to Washington, D.C. for a Slurpee Summit.  On Nov. 26, or “Purple Friday” as 7-Eleven has dubbed the…