This feels weird to set as default a variable using a third-party
service like Dropbox. Was OK when Spacemacs was less popular, now this
variable has nothing to do in this project.
With this new variable, user can load spacemacs anywhere, e.g.
"~/.emacs.d/spacemacs/". Only user's cache directory is still hard-coded
as "~/.emacs.d/.cache/". If user want to use spacemacs this way, drop
one line as the below in "~/.emacs.d/init.el":
(setq spacemacs-start-directory "~/.emacs.d/spacemacs/")
(load-file (concat spacemacs-start-directory "init.el"))
Now the user should use `SPC f e h` helm-spacemacs.
This is due to the fact that spacemacs layer is now a regular layer
stored in the "layers" directory.