Merge pull request #54 from zqjimlove/date

fix dateRange Bug
fixed slider bugs
Merge branch 'master' of https://github.com/dxq613/bui
fixed bug of calendar,fixed bug of slider
fix bug of slider
fixed form bugs
fixed bug #55
change keynav
fixed keynav bug
当设置minData或maxData,而今天非可选择范围之内.今天按钮将会disabled!