Add tsv to default acceptable upload extensiosn
Add tsv to default acceptable upload extensiosn

This is the extension that is added to tab-separated value files when exported
from google docs.

Fix #939

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