Added eval before the variable expansion
fish shell doesn't support to use variable as commands
(on purpose, see: http://lwn.net/Articles/136232/ "Impossible to Validate the Syntax" )
Make several variables constants.

While `defconst` will not prevent the user from altering a
variable's state, it conveys more clearly the fact that the
value of the particular variable is not meant to be changed.
Replace :else with t in a cond expression.

While the use of `:else` in a catch-all cond clause
is idiomatic in Clojure, in Emacs Lisp the idiom is to use `t`.
Merge pull request #192 from berdario/master

Make nrepl work with fish-shell
Merge pull request #213 from bbatsov/else

Replace :else with t in a cond expression.
Merge pull request #214 from bbatsov/constants

Make several variables constants.
Reset nrepl-buffer-ns on nrepl-restart.  Fixes issue #187.
Emit server log output at bottom of *nrepl-server* buffer.
Add nrepl-disconnected-hook and disable nrepl when disconnected.