Configure .gitattributes to manage line endings

Mark test resources as binary to prevent line ending normalization
Some of the test resources are used to test handling of line endings
in JGit.

Change-Id: Idd9ba604945797d1cd1f3af1a1987aee3188e1d6

.gitattributes

@@ -1,2 +1,14 @@
-*      text=auto
+* text=auto
+
+*.asc binary
+*.gif binary
+*.gitindex.dat binary
+*.key binary
+*.patch binary
+*.pdf binary
+*.png binary
+org.eclipse.jgit.test/tst-rsrc/org/eclipse/jgit/diff/** binary
+org.eclipse.jgit.test/tst-rsrc/org/eclipse/jgit/test/resources/** binary
+org.eclipse.jgit.test/tst-rsrc/org/eclipse/jgit/util/io/** binary
+
 *.java diff=java