Replace s-join for mapconcat function

This package requires the `s.el` library only for 2 occurences of
`s-join` function. `s-join` is only a wrapper for `mapconcat` so we don't
need to have the `s.el` library installed, we can use directly the
built-in `mapconcat` function !:)

helm-github-stars.el

@@ -69,7 +69,7 @@
     (disable-shortcuts)
     (init . (lambda ()
               (with-current-buffer (helm-candidate-buffer 'local)
-                (insert (s-join "\n" (hgs/get-github-stars))))))
+                (insert (mapconcat 'identity (hgs/get-github-stars) "\n")))))
     (candidates-in-buffer)
     (action . (lambda (candidate)
                 (let ((repo (substring candidate 0 (string-match " - " candidate))))
@@ -81,7 +81,7 @@
     (disable-shortcuts)
     (init . (lambda ()
               (with-current-buffer (helm-candidate-buffer 'local)
-                (insert (s-join "\n" (hgs/get-github-repos))))))
+                (insert (mapconcat 'identity (hgs/get-github-repos) "\n")))))
     (candidates-in-buffer)
     (action . (lambda (candidate)
                 (let ((repo (substring candidate 0 (string-match " - " candidate))))