Adding the ability to grh from a subdirectory

[cjappl]

Check list

• [x] I have performed a self-review of my code

Description

Closes #254

grh didn't work if you were in a subdirectory. From the issue ticket:

" Steps to repro

Change a file
git add the file
mkdir somesubdirectory && cd somesubdirectory
grh

Expected:

File show up in forgit, if you tab select them they get unstaged

Observed: Nothing to unstage. "

This should fix that.

Type of change

• [x] Bug fix

Test environment

• Shell
  • [ ] bash
  • [x] zsh
  • [x] fish
• OS
  • [x] Mac OS X

[cjappl]

Pinging @sandr01d as a reviewer if you're free :) thanks for the suggestion on #254 , you were exactly right with the --staged clue

[cjappl]

Thanks friends! Merging