Define colors for ace-jump-mode

I use fg-red and fg-base01 for the red and gray40, respectively, tht
ace-jump-mode.el uses:

https://github.com/winterTTr/ace-jump-mode/blob/07b7137/ace-jump-mode.el#L303
https://github.com/winterTTr/ace-jump-mode/blob/07b7137/ace-jump-mode.el#L297

The original Vim plugin also recommends red and comment (faded), which is
what the above accomplishes:

https://github.com/Lokaltog/vim-easymotion/blob/eaa4af/doc/easymotion.txt#L992