plus.gallery.pick的参数中设置了multiple : true,点击一张图片后就立马返回了，不能同时多选几张图片

var btn = document.getElementById('gallary'),
content = document.querySelector('.msgSection');
btn.addEventListener('tap',function(){
plus.gallery.pick(function(path){
var img = '';
for ( var i in path.files ){
img += '<img width=100 class="chat-img" src='+path.files[i]+'/>';
}
content.innerHTML = img
},function(e){
content.innerHTML = e.msg;
},{
filter : "image",
multiple : true,
maximum : 3
})
})