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/nginx-vim/indent/nginx.vim

@@ -0,0 +1,9 @@
+if exists("b:did_indent")
+    finish
+endif
+let b:did_indent = 1
+
+" cindent actually works for nginx' simple file structure
+setlocal cindent
+" Just make sure that the comments are not reset as defs would be.
+setlocal cinkeys-=0#