Use forked version of zsh-git-prompt

- main project installed via homebrew appears to not be maintained
- add instructions to clone done fork, which has bug fixes and feature
  to show stash
- create .gitignore to not add zsh-git-prompt repo to source control
- see this issue for more info: olivierverdier/zsh-git-prompt#123

.gitignore

@@ -0,0 +1 @@
+zsh-git-prompt/

Brewfile

@@ -18,7 +18,6 @@ brew "tree"
 brew "vim"
 brew "yarn", args: ["without-node"]
 brew "youtube-dl"
-brew "zsh-git-prompt"
 brew "heroku/brew/heroku"
 brew "joshuaclayton/formulae/unused"
 cask "qlcolorcode"

zshrc

@@ -5,8 +5,9 @@ eval "$(hub alias -s)"
 eval "$(thefuck --alias)"
 eval "$(rbenv init -)"
 
-if [ -f "$(brew --prefix)/opt/zsh-git-prompt/zshrc.sh" ]; then
-  source "$(brew --prefix)/opt/zsh-git-prompt/zshrc.sh"
+# run `git clone [email protected]:starcraftman/zsh-git-prompt.git`
+if [ -f "zsh-git-prompt/zshrc.sh" ]; then
+  source "zsh-git-prompt/zshrc.sh"
   PROMPT='%(?.%F{green}√%f.%F{red}?%?%f) %F{yellow}%~%f $(git_super_status)
 %F{7}%T%f %# '
 fi