A very simple "make test" that uses cram and contains one test

Based on the fine work by @sjl a year ago:

https://github.com/sjl/the_silver_searcher/tree/958b693a2b830fa2f6bf31b4ae76bfcae5a6d3fc

To use:

```bash
$ sudo easy_install cram
$ ./build.sh
$ make test
```

Might be a way forward with #73 and #281.

Cram seems easy to use and gets the job done. Note that it runs tests in a tmp dir. You have to alias ag so that it runs your development ag instead of the system one. That's what `source setup.sh` is doing... Again, this is all originally from @sjl.

One caveat - I had to specify the name of the input file ("sample") in order to make the tests work. Perhaps some enterprising soul can figure out why?

Pardon my incompetence. I don't really know anything about automake, cram, python, etc. :)