BUG: Catch error and format it properly
BUG: Catch error and format it properly

QiitaDuplicateHeaderError was not being caught and thus was not showing
any message via the GUI.

Fixex #648

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