Add config for mackup

- ignore apps whose config files are in the `dotfiles` repo
  (see: https://gitlab.webartifex.biz/alexander/dotfiles)
- include various (config) files that should not be public:
  + Cisco's AnyConnect
  + history files for `bash`, `less`, `python`, `psql`, `tig`, and `zsh`
  + Nautilus' bookmarks
  + SSH config & known hosts

.mackup/histories.cfg

@@ -0,0 +1,13 @@
+[application]
+name = various history files
+
+[configuration_files]
+.bash_history
+.lesshst
+.python_history
+.tig_history
+.zsh_history
+
+[xdg_configuration_files]
+# `~/.config/psql` is set in `~/.psqlrc` for all history files
+psql