Prefer :all over other meta while merging profile.

If project.clj looks like

```clojure
...
:aot [mynamespace]
:profiles {:myprofile {:aot :all}}
```
`lein with-profiles +myprofile <task>` will warn *[mynamespace] and :all have a type mismatch merging profiles* and will pick one which is merged last. IMO :all should be prefered over collection of namespaces.