added a very simple test suite

How to use:
1) Place a source file (*.cpp) containing the code to test in the tests/
   directory
2) Place the following line somewhere in your source file:
   "// $RESULT: <N>" where <N> is the expected return value
3) run `make' to compile all source files to %.ll and their binary
4) run `make check' to run the test script
added example default.cfg file

do `cp example.default.cfg default.cfg' and edit the CXX flag to match your path
to the Sierra clang binary