Fix .gitmodules

Remove jrl-cmakemodules because it is called two times and because of that the release in the ros buildfarm did not work.

.gitmodules

-[submodule "jrl-cmakemodules"]
-	   path = jrl-cmakemodules
-	   url = git://github.com/jrl-umi3218/jrl-cmakemodules.git
 [submodule "cmake"]
 	path = cmake
 	url = git://github.com/jrl-umi3218/jrl-cmakemodules.git