Be conservative about what to add to $LOAD_PATH

The promiscuous loading of everything in the project dir
results in 10+ seconds execution time of all specs whereas
this version is just 2+ seconds.
Use Guard

This will eliminate the need to alt-tab between editor and terminal
just to run the tests and see the results.
Merge pull request #57 from relaxdiego/faster_specs

Modify how specs are executed to improve execution speed