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/snipmate-snippets/c/once.snippet

@@ -0,0 +1,6 @@
+#ifndef ${1:`toupper(Filename('', 'UNTITLED').'_'.system("/usr/bin/ruby -e 'print (rand * 2821109907455).round.to_s(36)'"))`}
+#define $1
+
+${2}
+
+#endif /* end of include guard: $1 */