Merge branch 'submodule_versions' into 'master'

fix git submodule versions, no branch tracking

See merge request !364

.gitmodules

 [submodule "modules/data"]
     path = modules/data
     url = ../../AirShowerPhysics/corsika-data.git
-    branch = master
     shallow = true
 [submodule "modules/conex"]
 	path = modules/conex
 	url = ../../AirShowerPhysics/cxroot.git
-	branch = master
 	shallow = true