update Umeng Social SDK to 3.3.7.1
Merge pull request #19 from Gavin-Ye/master

commit message test
update Umeng Social SDK, modify .podspec file
Merge pull request #20 from Gavin-Ye/master

commit message test
Merge pull request #11847 from umeng/master

ADDED:UMengSocial 3.3.7.1