Add cbjohnson theme.

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