add view outside for captcha gif

webqq开始使用gif作为验证码了,导致pidgin只能显示1帧,本补丁暂时把以前的
cancel换做view outside,调用xdg-open来打开写入本地的gif文件,作为临时解决
方案.

Signed-off-by: xiehuc <xiehuc@gmail.com>
Merge branch 'upstream/dev' into unstable