.gitattributes: let git normalize all line endings

Everything should be careful, but don't let things get troublesome.
I don't want to change the .gitattributes frequently, but the
attributes for cross-platform is not friendly, and very easy to
create mixed line endings, nobody want to see.

Modify .gitattributes and bring back some old settings.

.gitattributes

@@ -1,2 +1,16 @@
-# hosts file always be normalized on checkin
+# Set the default behavior, in case people don't have core.autocrlf set.
+* text=auto
+
+# hosts file always be normalized on checkin.
 hosts text
+
+# Always be normalized to LF line endings on checkin and converted files
+# to native line endings on checkout.
+*.md text
+*.yml text
+*.sh text
+Hindent text
+lhosts text
+
+# Don't modify binary files.
+*.zip binary