Add testing infrastructure

[rogersm]

Some small steps to add testing infrastructure to close Issue #11:

1. For the tests to run Check needs to be installed in your OS or vagrant.
2. Tests should be written in the $(ROOT)/tests/ directory using the check syntax.
   Additional info can be found reading the man page:

# man checkmk

3. Also, tests can be coded directly in C in $(ROOT)/tests/ directory, no problem with that. I plan to add a sample shortly, but if you do it before me and the Makefile is unable to compile them, please open an issue and I'll check.
4. Test samples are fairly inconsequential :)
5. The Makefile doesn't run the tests, this has to be done manually or via CI running the binaries compiled by the Makefile in $(ROOT)/tests/ directory. They can be identified by the .run extension. @zachflower can you add them to Travis CI?

[xenith]

Why are you disabling -g? I'd think we'd want debugging information in the binaries so core dumps are readable.

[zachflower]

I think requiring check in macOS is fine, but let's make sure to keep the development environment in Vagrant up to date, since it can be provisioned automatically. Would you add a check provisioner, please?

There are two places to do this, the first is the provisioner script (take a look at vagrant/provisioners/c.sh for a solid example) and the second is in the Vagrantfile itself (where the provisioner scripts are executed).