Updated all plugins that are non-forked. Added some new plugins.

Added update_plugins.py which can fetch new plugins from GitHub.

New plugins added: zencoding, vim-indent-object, taglist, nginx.vim

sources_non_forked/vim-snippets/UltiSnips/json.snippets

@@ -0,0 +1,19 @@
+snippet s "String" b
+"${1:key}": "${0:value}",
+endsnippet
+
+snippet n "number" b
+"${1:key}": ${0:value},
+endsnippet
+
+snippet a "Array" b
+[
+   ${VISUAL}$0
+],
+endsnippet
+snippet o "Object" b
+{
+   ${VISUAL}$0
+},
+endsnippet
+