Add directory to fix object extensions loaderror

Because the file object_extensions.rb is in
lib/object_extensions/object_extensions.rb (I think), I and travis were
getting "LoadError: cannot load such file -- object_extensions". This
fixes the error... there might be a better way to fix this though.
Merge pull request #4 from carols10cents/fix-object-extensions-loaderror

Add directory to fix object extensions loaderror