core/prelude-packages.el: Add helm-projectile and key-chord

When using option "(byte-recompile-directory user-emacs-directory 0)",
it throws the following error messages when starting Emacs with prelude
for the first time:

prelude-helm.el:37:1:Error: Cannot open load file: helm-misc
prelude-key-chord.el:37:1:Error: Cannot open load file: key-chord