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

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

themes/will/README.md

-## Will
-Minimalist theme.
-
-![Screenshot](https://cloud.githubusercontent.com/assets/143746/6462675/60d171fe-c1ab-11e4-9434-8718a2139c79.png)
-
-#### Characteristics
-* The current working directory is displayed on the right-side
-* Hostnames are displayed if and only if we're on an SSH connection
-* Uses logical entailment as the prompt character

themes/will/fish_prompt.fish

-function fish_prompt
-  if test -n "$SSH_CONNECTION"
-    printf '%s ' $HOSTNAME
-  end
-
-  set_color red
-  printf "⊨"
-  set_color normal
-  printf " "
-end

themes/will/fish_right_prompt.fish

-function fish_right_prompt
-  set_color red
-  printf '%s ' (prompt_pwd)
-  set_color normal
-end