add (jda-gf-find-file-dired)

* (jda-gf-find-file-dired) is bound to "C-c j F".
to use (dired-nondirectory-p)
improve (jda-build)

* use (jda-read-shell-command) instead of (read-from-minibuffer)
* use (directory-file-name) instead of (file-name-as-directory)