树形控件标准化微调

- 更改项目名
- 树 demo 修改
- less 统一引入变量
- resolve https://github.com/ecomfe/ub-ria-ui/issues/35
- resolve https://github.com/ecomfe/ub-ria-ui/issues/31
- resolve https://github.com/ecomfe/ub-ria-ui/issues/30

项目迁移需将模块名从 ub-ria/ui/xxxSelector 改为 ub-ria-ui/xxxSelector