Remove python 3 from travis CI
Remove python 3 from travis CI

We should add it back in when biom is python 3 compatible

ElDeveloper/qiita,josenavas/QiiTa,wasade/qiita,biocore/qiita,biocore/qiita,RNAer/qiita,ElDeveloper/qiita,squirrelo/qiita,wasade/qiita,biocore/qiita,adamrp/qiita,ElDeveloper/qiita,adamrp/qiita,adamrp/qiita,RNAer/qiita,RNAer/qiita,wasade/qiita,biocore/qiita,antgonza/qiita,squirrelo/qiita,antgonza/qiita,josenavas/QiiTa,josenavas/QiiTa,ElDeveloper/qiita,squirrelo/qiita,squirrelo/qiita,antgonza/qiita,josenavas/QiiTa,adamrp/qiita,antgonza/qiita,RNAer/qiita