Add habitat plan

[themightychris]

This provides an easy way to install the command onto systems, and has the benefit of running git-subsplit under a consistent bash version

The habitat binary can be installed with this one-liner:

curl -s https://raw.githubusercontent.com/habitat-sh/habitat/master/components/hab/install.sh | sudo bash

I've published a build to my own origin, which you can install like this:

hab pkg install jarvus/git-subsplit

The maintainer of this repo could sign into https://bldr.habitat.sh with their github account, register the origin dflydev, and configure habitat's public builder to automatically create new builds whenever the master branch in this repo is updated.

Alternatively, someone cloning this repository could just run:

hab pkg build .
sudo hab pkg install ./results/*.hart

Once the package is installed to a system, this command can be run to install the binary to the needed path:

sudo hab pkg binlink -d "$(git --exec-path)" jarvus/git-subsplit

Final result

With a dflydev origin setup on bldr.habitat.org and linked to the repository, these commands could be used in a CI process at any time to quickly and consistently load the latest version:

# install habitat client binary
curl -s https://raw.githubusercontent.com/habitat-sh/habitat/master/components/hab/install.sh | sudo bash

# install git-subsplit package
sudo hab pkg install dflydev/git-subsplit

# add to system's git subcommands
sudo hab pkg binlink -d "$(git --exec-path)" dflydev/git-subsplit

Bonus points

Tag a release version on the master branch in this repo and the habitat build will pick it up