remove range v3 (#101)

Summary:
As above

Pull Request resolved: #101

Reviewed By: Alston-Tang

Differential Revision: D42762460

Pulled By: briancoutinho

fbshipit-source-id: ec3d86527e1009614379f93bef403c613413482f

.gitmodules

@@ -16,9 +16,6 @@
 [submodule "third_party/googletest"]
 	path = third_party/googletest
 	url = https://github.com/google/googletest.git
-[submodule "third_party/range-v3"]
-	path = third_party/range-v3
-	url = https://github.com/ericniebler/range-v3.git
 [submodule "third_party/cpr"]
 	path = third_party/cpr
 	url = https://github.com/libcpr/cpr.git