1. Private layers

It is now possible to reload the dotfile and layers anywhere with `SPC f e
R`. This key binding **replaces** the old `C-c C-c` and `SPC m c c` only
available in the dotfile.

**Important** You should replace your `(defvar <layer>-packages ...)`,
`(defvar <layer>-pre-extensions ...)`, `(defvar <layer>-post-extensions ...)`
and `(defvar <layer>-excluded-packages ...)` by `(setq ...)`. This will
allow to install newly added packages to a layer without restarting spacemacs
by pressing `SPC f e R`. Be sure to remove the docstring when replacing the
`defvar` since `setq` does not take a third argument. 

2. Emacs lisp is now in its own layer

Be sure to add the new layer `emacs-lisp` to your dotfile to continue
to enjoy the emacs-lisp configuration of Spacemacs.

3. Key bindings

`SPC b s` to switch buffer is now on `SPC b b`
`SPC f f` uses helm instead of ido