git-checkout-store: Create an rc file if it doesn't exist
git-checkout-store: Create an rc file if it doesn't exist

Make a `.git-checkout-historyrc` file in the current user's home
directory if the file doesn't exist.

Resources:
- [Path to home
  directory](http://stackoverflow.com/questions/7922270/obtain-users-home-directory)
- [Cross-compilation version](https://github.com/mitchellh/go-homedir)

teddywing/git-checkout-history