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/snippets/ledger.snippets

@@ -0,0 +1,5 @@
+# Ledger <http://ledger-cli.org/>
+snippet ent
+	`strftime("%Y/%m/%d")` ${1:transaction}
+	    ${2:account}    ${3:value}
+	    ${4:account}