adding global gitignore for KDevelop4

KDevelop4 is the C/C++-IDE from the KDE desktop.
It creates a directory '.kdev4' and a hidden file
<projectname>.kdev4 in the project's root directory.

Global/KDevelop4.gitignore

@@ -0,0 +1,2 @@
+*.kdev4
+.kdev4/