Update runtime files. Make matchparen plugin backwards compatible.

Add json filetype.

runtime/ftplugin/json.vim

@@ -0,0 +1,17 @@
+" Vim filetype plugin
+" Language:		JSON
+" Maintainer:		David Barnett <daviebdawg+vim@gmail.com>
+" Last Change:		2014 Jul 16
+
+if exists('b:did_ftplugin')
+  finish
+endif
+let b:did_ftplugin = 1
+
+let b:undo_ftplugin = 'setlocal formatoptions< comments< commentstring<'
+
+setlocal formatoptions-=t
+
+" JSON has no comments.
+setlocal comments=
+setlocal commentstring=