When pull request #3855 was cherry picked in (due to conflicts),
spacemacs/elm-repl-push-decl-focus was incorreclty referenced as
spacemacs/elm-repl-push-decl in the keybindings.
Upstream elm-mode renamed REPL related functions from *-elm-repl to
elm-repl-*, but the elm layer was still referencing the old names (except
for elm-repl-load which had previously been fixed).
Helm seems to treat "!" specially in pattern matching, so having a ! in
the pattern string when traversing directories is problematic. This
change fixes#2737, because as far as I can tell "+" has no special
meaning in a helm pattern.
Of course, we can choose a different character, but I'm fond of "+" as
representing "more layers here".
