[split] Move cbjohnson theme to oh-my-fish/theme-cbjohnson

https://github.com/oh-my-fish/theme-cbjohnson

themes/cbjohnson/README.md

-## cbjohnson theme
-
-A minimal theme forked from the [yimmy][yimmy-commit] theme (thanks [jhillyerd][yimmy-author]!)
-
-![screenshot](https://cloud.githubusercontent.com/assets/4823640/5327427/6f9e61bc-7d02-11e4-9223-38ddbed176c8.png)
-
-[yimmy-commit]: https://github.com/bpinto/oh-my-fish/tree/3a4b7de689cabf3522227f51177a489d915c8b4d/themes/yimmy
-[yimmy-author]: https://github.com/jhillyerd

themes/cbjohnson/fish_prompt.fish

-function fish_prompt
-  # Cache exit status
-  set -l last_status $status
-
-  # Just calculate these once, to save a few cycles when displaying the prompt
-  if not set -q __fish_prompt_hostname
-    set -g __fish_prompt_hostname (hostname|cut -d . -f 1)
-  end
-  if not set -q __fish_prompt_char
-    switch (id -u)
-      case 0
-        set -g __fish_prompt_char \u276f\u276f
-      case '*'
-        set -g __fish_prompt_char »
-    end
-  end
-
-  # Setup colors
-  set -l normal (set_color normal)
-  set -l cyan (set_color cyan)
-  set -l yellow (set_color yellow)
-  set -l bpurple (set_color -o purple)
-  set -l bred (set_color -o red)
-  set -l bcyan (set_color -o cyan)
-  set -l bwhite (set_color -o white)
-
-  # Configure __fish_git_prompt
-  set -g __fish_git_prompt_show_informative_status true
-  set -g __fish_git_prompt_showcolorhints true
-
-  # Color prompt char red for non-zero exit status
-  set -l pcolor $bpurple
-  if [ $last_status -ne 0 ]
-    set pcolor $bred
-  end
-
-  # Top
-  echo -n $cyan$USER$normal at $yellow$__fish_prompt_hostname$normal in $bred(prompt_pwd)$normal
-  __fish_git_prompt
-
-  echo
-
-  # Bottom
-  echo -n $pcolor$__fish_prompt_char $normal
-end