Update course title

PREPARATIONS.md

-# Preparations for course: Data management with GitLab
+# Preparations for course: Code and data management with Git
 
 - Date: December 1st, 2015
 - Time: 9:00 - 17:00
@@ -50,4 +50,4 @@ Our current list (not yet confirmed):
 - Jonathan Vis
 - Thomas Chin-A-Woeng
 - Sake (?)
-- Niels (?)
+- Niels (?)
\ No newline at end of file