Test suite boilerplate and Leaflet build update to 0.6

I took a shot at adding a test suite for #26. I aimed to use the same tools as the Leaflet project. I really like Grunt.js, so I used Grunt.js rather than Jake, but that would be easy to swap out. I'm not sure I like how I organized the tests, but I think the boilerplate for the test framework is a reasonable place to start.

This also upgrades the examples/lib/Leaflet build to a more recent 0.6 version. I added examples/markers.html to test adding 100 markers to the map. For some reason when the control was listening to 'layeradd' and 'layerremove', the browser was crashing when adding layers using newer Leaflet builds; usually somewhere after 10 markers or so. Listening to the new 'zoomlevelschange' seems to fixed it, but may have other implications.

Sorry there are so many changes in this one pull request. Let me know if you'd like for me to break them up.

I'm planning on taking a crack at some 0.6 style updates today as well.

Cheers,
- Bryan