feature：添加接受群邀请接口

[leochen-g]

先留个记录，web协议是支持接受群邀请的，后续提交pr实现

setCheckUrl: function(accountFactory){
	            _checkURLsuffix =
	                "&skey=" + encodeURIComponent(accountFactory.getSkey())
	                + "&deviceid=" + encodeURIComponent(accountFactory.getDeviceID())
	                + "&pass_ticket=" + encodeURIComponent(accountFactory.getPassticket())
	                + "&opcode=2&scene=1&username=" + accountFactory.getUserName();
},
genCheckURL: function(url){
	            if(!_checkURLsuffix) throw "_checkURLsuffix is not ready!";
	
	            return confFactory.API_webwxcheckurl +
	                "?requrl=" + encodeURIComponent((url.indexOf("http") == 0 ? "" : "http://") + service.clearHtmlStr(service.htmlDecode(url))) + _checkURLsuffix;
	       },

[spacelan]

👍🏻