Fixed slider.less compile errors
Compiled slider.less to slider.css
Fixed border radius

Old value was 20px, less file for some reason used 4px, I think it's
better to use 50%.
Fixed round border

Original value: 20px
Less value: 4px
I think it's better as 50%
Added less compiling to grunt file
No need for full path in slider.less with grunt task
Merge pull request #29 from rahatarmanahmed/dev-less-compiler

Dev less compiler