Merge pull request #87 from liaoxuezhi/dev-refactor

Dev refactor
case 补充sliler lazyloadimg loop=true
slider dynamic增加测试点:
slideTo //index === to   不做操作
slideTo //index === this._circle( to )  不做操作
active  //测试active
content //改变内容，选中的是最后的
content //center=true，改变内容，选中的是中间的
Merge pull request #89 from yancend/dev-refactor

case 补充sliler lazyloadimg loop=true
优化slider
merge some case