PLUGINS: vi-mode: allow ctrl-p, ctrl-n for history navigation

Allow ctrl-p, ctrl-n for history navigation while in insert mode.

plugins/vi-mode/vi-mode.plugin.zsh

@@ -34,6 +34,10 @@ bindkey -v
 autoload -Uz edit-command-line
 bindkey -M vicmd 'v' edit-command-line
 
+# allow ctrl-p, ctrl-n for navigate history (standard behaviour)
+bindkey '^P' up-history
+bindkey '^N' down-history
+
 # if mode indicator wasn't setup by theme, define default
 if [[ "$MODE_INDICATOR" == "" ]]; then
   MODE_INDICATOR="%{$fg_bold[red]%}<%{$fg[red]%}<<%{$reset_color%}"