Bump SnipMate engine version from 0 to 1. (carlhuda#712)

`vim-snipmate`[1] has moved from engine version 0 to version 1. The
result is that starting vim with janus produces a deprecation
warning upon starting either vim or gvim. Simply instructing SnipMate to
use the new engine fixes the issue.

Closes: carlhuda#712

[1] https://github.com/garbas/vim-snipmate

janus/vim/core/plugins.vim

@@ -40,3 +40,7 @@ endif
 if exists("*DetectNode")
   call janus#disable_plugin("nodejs", "Nodejs already exists on your system.")
 endif
+
+" SnipMate needs to be told to use v1 engine
+" See #712
+let g:snipMate = { 'snippet_version' : 1 }