lem.el 0.12 - optional encrypted auth tokens

I recently updated lem.el to 0.12.

The release makes encrypted tokens optional for easier use. If you update and find you can’t load lem.el, delete ~/.emacs.d/lem.plstore and log in again. If you want your auth tokens to be encrypted, set lem-encrypt-auth-tokens to non-nil. You’ll also need to set plstore-encrypt-to to a GPG key of yours.