Description of problem: Improve multi file upload dialog to support document types selection if the file extension is found in multiple org.zanata.common.DocumentType. There's no use cases prior https://bugzilla.redhat.com/show_bug.cgi?id=1186972. But with the support of properties and properties_utf8, xml and xliff in file project type, we need to update the upload dialog to allow selection from user when uploading.
Migrated; check JIRA for bug status: http://zanata.atlassian.net/browse/ZNTA-81