Added a simple test to verify it works

So, I got further along now, but I get a segmentation fault if I run this test; I assume this should work?
```
tojans@ubuntu:~/develop/erlang/fdb-erlang/deps/gen_driver$ ./rebar compile eunit
==> gen_driver (compile)
==> gen_driver (eunit)
basic_test: basic_test (module 'basic_test')...*failed*
in function gen_driver_test:sum/3
  called as sum(1,2,97)
in call from basic_test:'-basic_test/0-fun-0-'/1 (test/basic_test.erl, line 8)
in call from basic_test:basic_test/0 (test/basic_test.erl, line 8)
in call from basic_test:basic_test/0
**error:undef


=======================================================
  Failed: 1.  Skipped: 0.  Passed: 0.
Segmentation fault (core dumped)
```