Initial Bats scaffold (DO NOT MERGE)

[hyperupcall]

The purpose of this PR is to better show the additions that might be made to incorporate Bats, a testing framework for Bash. More information about this PR can be found in this comment.

To run this code, be sure to:

1. Install Bats (see instructions on Bats website)
2. Switch to this branch (this branch adds a git submodule, hyperupcall/bats-all, be sure to update submodules (i think that git submodule update --init should do the trick))
3. Now you can run bats ./tests

When executing Bats, Bats will look for files inside of ./tests that end with .bats. If it sees any, it "executes" it. In this PR, there are two .bats files used to demonstrate a few features of Bats.