Ensure integration tests cover nrepl startup

[trptcolin]

In a recent change, lein trampoline run failed, but the test suite didn't catch it (😿) because the nrepl integration spec currently attaches to an nREPL server that's spun up in setup, then uses :attach.

This leaves the nrepl integration under-exercised by tests, which is now an issue due to the more active development and potential breaking changes there.

I'd be happy with another few tests like the existing ones, but run without the :attach assumption, where the server can be spun up inline. If necessary (due to port assumptions, TravisCI, or whatever), they could be done in a bash script instead of in clojure-land.

[bbatsov]

@trptcolin Do you need any help with that? I thought that it was going to be enough just to remove the deref.

I'm asking because a few users mentioned that now they get:

java.lang.Exception: No namespace: reply.eval-modes.nrepl found

which is this problem, so I'd like to fix this in REPL-y and update the dep in Boot and Lein.