Update directories naming and version release

Hi!

I made some changes, I hope they are ok!

- Rename "_attention" to "_attention-seekers" (as in animate.css original repo)
- Split "_sliders" to "_sliding-entrances" and "_sliding-exits"
- Compile a nested animate.css with sourceMap
- Compile a compressed animate.min.css with sourceMap
- update the release number in bower.json