修改 bee new 命令执行路径问题

执行 bee new 路径应该在`${GOPATH}/src` 下, 在 `${GOPATH}`下执行会提示  

    2014/09/02 16:06:25 [ERRO] Unable to create an application outside of $GOPATH(/foo/bar)
    2014/09/02 16:06:25 [HINT] Change your work directory by `cd ($GOPATH/src)`