Improvements

1. Improvements in js file:
  * work with row classes odd and even
  * set fixed width to cells while sorting
  * on save send only one ajax request with order for changed rows
2. Added styles for handler
3. Changed handler icon for more obvious for most people
4. Added install generator

Please tell me if you have any notices about my code.

Thank you, neo for all time you spent on this small gem, it helped me a lot!