Attempt to avoid errors on aliased 'contains'

Users with vim-clojure-static and vim-clojure-highlight see errors and broken highlighting when opening some test files. The culprit is `[midje.sweet :refer :all]` as that includes a function `contains`. And this is illegal in Vim:

```vim
syntax keyword clojureFunc foo contains bar
" E395: contains argument not accepted here
```

Similarly a couple of other words (oneline, concealends) will not be recognised; but I'd be very surprised if they turned up in much code!

Note that my example code attached still doesn't highlight 'contains' correctly - for the life of me I can't figure out why as the regular expression generated appears under clojureFunc when I call `:syntax` and pasting that regexp into a manual `:syntax match` is fine.