add timeout set to every img download urlopen
fix:non img src url matched getOnePagePicUrl error

for the reason that i use re.compile \S+(jpg|png)
to match img src,when a gif pic come,the regular
search can't match,so the result is none.But I forgot
to deal with this situation. Now , I first judge the
result,then append to imgUrls when it can
the same as last commit
Merge branch 'master' of https://github.com/linuxhenhao/SearchEnginePicDownloader into dev

Conflicts:
	README.md